Perhaps - personally, I support many independence movements even if they're not socialist or communist, because often its impossible to progress while occupied or colonised, so its a necessary first step. Afghanistan is a good example of this - its objectively better having the Taliban back in control than the US occupation and their pet warlords.

I see what you mean in a strategic sense - its not a good idea to fight against too many opponents at once. I'm not sure that Shining Path did attack those who they should have allied with however - all the sources I can find are dubious, and I wasn't there, so I can't really make a good judgement about who did what and the types of people they are alleged to have killed, only apply the usual rubric that if the US says one thing about communists, the opposite is probably the case.

From what I've read, it seems like they did have a lot of support (and what they did achieve would be frankly impossible without that). The difference I can see between them and the Maoist case, is that Peru wasn't being occupied by another power at the time, and the urban centres didn't like them so much (except in the very poor areas). But then Peru isn't/wasn't particularly industrialised, being a resource extraction colony, so I wonder if there was even a significant urban proletariat to really bother trying with.