There have been registered convictions for this infraction, look at CanLaw. Someone here posted the link to it I think two seasons ago, it included the JP's decision, and his reasoning, for registering the conviction. Keep in mind, just because your friend is a crown, doesn't mean he knows every case, nor every regulation, just as not all police officers know, every section, or the HTA. If memory serves me correctly the JP cited that the mounted camera, did indeed affect the structural integrity of the helmet, but also, cited that during a collision the camera could become dislodged, and therefore, presented the additional risk of becoming a "flying projectile"
Painting of a helmet, does not affect the integrity of the outer shell. If you also look closely somewhere in that section it states anything that "protrudes more than 5mm, which is not installed by the manufacturer" is what changes the helmet integrity. One would have to apply MANY MANY coats of paint to exceed 5mm..lol
Besides the hassle of going to court, a good crown, will simply point to the previous convictions, and as you know unless it is an appellant court hearing the case, these cases are heard by JP's with no formal legal training, so they are VERY likely to follow, what previous JP's have ruled. Going to an appeal can be pretty costly, which is why thus far no one has gone that route for a simple ticket.
As for your assertion that the law is "very very literal" and one can not "assume the meaning of what it is saying" this is an incorrect statement. The HTA in particular, is a VERY poorly worded document, with MOST regulations/sections, purposely written somewhat vaguely and open to interpretation. Crowns, Police Officers and JP's therefore, routinely, apply their interpretation of the various regulations/sections daily. However, having said that the ONLY interpretation that counts in the end is that of the presiding JP, Then if appealed, the appeal court, hearing the case.
When a JP makes a ruling, then it can be used as "case law". Then if an appeal court, (with competent jurisdiction), hears a case, and publishes it's verdict, then that case becomes "precedent setting" meaning that if quoted during a trial a lower court is bound to rule in the same manner, (unless of course the case is appealed to a higher court, again with competent jurisdiction.
Now as I have said in the past, I used to ride with a Go Pro attached to an old helmet and never, was hassled over it, (in fact I ad a "rolling conversation" with an OPP officer along the 401 as we were stuck in stop and go traffic). That doesn't mean, that because I had that conversation, and wasn't cited, that it was now "magically legal", it merely meant that either the officer, was unaware of the regulation, or he felt it was not an issue in his mind. I wouldn't advise other riders to mount their camera on their helmet, (I moved mine to the bike), and bought a special wiring harness that then meant, it was hard wired to the bike so no more running out of battery, during a ride. Does it mean just because you have a camera mounted your going to be stopped? Not at all, in fact chances are pretty slim, (just as they are if you have a single beer and drive/ride home). BUT, it does give an officer the "option" of pulling you over, in hopes of discovering other infractions. When I was a copper MANY if my impaired cases came not from erratic driving but from other infractions, (IE speeding, seat belts etc). So then the question becomes, is it worth the hassle to catch the view from your helmet as opposed to the bike? I personally dislike the "helmet videos" simply because there is way too much head movement, as opposed to bike videos.
I have a camera mounted on handlebars, (which also gave the added bonus of no potentially incriminating speedometer shots..lol), as well as rear facing camera. Both cameras were to capture if a collision occurred. The rear facing camera was added after I was rear ended in stop and go on the 401 by another bike. BUT, one also has to remember that a camera can be a double edged sword, Yes, it may capture another driver/rider doing something stupid or illegal to cause a collision, BUT, it may also capture YOU doing something, which will change the fault determination.
Regarding the helmet issue, I know an MTO Crown Prosecutor personally so I will ask how this will be treated in court. If you're looking at subsection 1, clause c and d:
(c) have a hard, smooth outer shell lined with protective padding material or fitted with other energy absorbing material and shall be strongly attached to a strap designed to be fastened under the chin of the wearer; and
(d) be undamaged from use or misuse. R.R.O. 1990, Reg. 610, s. 1
It seems to be a matter of definitions...keep in mind the law is very, very literal. You have to read it word by word and not assume the meaning of what it is saying.
Does the helmet have a smooth outer SHELL? Well yes it does, the SHELL is smooth and the SHELL hasn't been modified if you are affixing something on top of it without modifying the structure of the shell such as screwing something into it. What about something like painting it? Does the extra weight and thickness of the paint cause the shell to have a different structural integrity and can it still absorb damage? Or will the paint chemicals eat away at the outer shell?
Does these things count as misuse? Likely not in the eyes of any good Justice of the Peace. Keep in mind the cop can lay a charge but that doesn't mean it's correct. The hassle is taking the time to go to court if you get charged.