If your audience cares significantly about the charitable donations and not at all for animal suffering, and your goal is to only to convince them to be against the company, then sure, go for it.
But any effective altruist should have their goals set higher than this, at actually reducing the insane amount of suffering that's created. It does very little good if everyone stops supporting Chik-Fil-A only to flock to another chicken company, which will be the same in almost every way, possibly minus some donations, possibly one which treats animals even worse. Effective altruism is a very different beast than simply appealing to or signaling the crowds' most popular views on ethics in order to persuade.
But any effective altruist should have their goals set higher than this, at actually reducing the insane amount of suffering that's created. It does very little good if everyone stops supporting Chik-Fil-A only to flock to another chicken company, which will be the same in almost every way, possibly minus some donations, possibly one which treats animals even worse. Effective altruism is a very different beast than simply appealing to or signaling the crowds' most popular views on ethics in order to persuade.