So... a few people will boycott them.. who may or may not buy from them, directly, might still indirectly, will surely instill fear into these people and make them care.
I always try to go to Wawa for gas (same price cash/credit? cheaper prices than everyone else? yeah!), and even then, there aren't a lot of BP's where I live. I'll definitely go out of my way to avoid them, even if they're my only choice.
I usually buy my gas from BP actually, I have for years since there was one in a good location (prices a little higher than the wawa, but the wawa was always busy and in a terrible location). I moved, but I've still been buying from a BP just out of habit (the location isn't particularly good or bad here). Maybe I'll just get gas from the sheetz, but who the knows where their gas comes from anyway? It says in their FAQ that they don't really know where it comes from since that shit all gets mixed together.