Probably since Merle is pretty much the only candidate to mirror the "Governor" character.
I was thinking the same thing when they first encountered the bandits outside the bar and one of them said something like "I'm not going back to face him with that news"...
Some of the story follows the original but a lot of it goes in a different direction.
I was surprised to see Shane lasted so long since Carl kills him (to defend Rick) early in the story.... maybe that's Shane's fate later on.
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