The engine temp issue for snowmobiles is keeping them cool, not getting them warmer. They have no problem heating up, and having the oil at proper running temps. Probably due to being enclosed in tight quarters, unlike a motorcycle engine that's not as well insulated. Plus, they'll run 0 weight oils. I don't think any motorcycle engine is rated for o weight oils.
They still cool just as fast as any other engine. Come to think about it, how do cars not snap valves constantly all winter?