If you think a company has behaved badly, why are you under any obligation to be fair to them?
It might be extremely difficult to boycott every company involved, so why not choose one to make an example of? The idea that you must boycott all or none appears irrational.
It's as though you're being bullied by two people, and when you try to deal with one of them, you're accused of being unfair because you can't deal with both!
It sounds very much as though it was the bullies who decided what was "fair" in this instance.
