You're being too charitable. By their definition of "exploit", anyone holding crypto and benefiting from capital gains is "exploiting", since these people are also benefiting off a system based on "massive electrical waste".

Is there a term for someone who stretches language in such a way for rhetorical purposes?

I can see why it's an effective rhetorical trick, since it forces people to debate whether the behavior is bad enough to fit the definition of exploitation, or whether it's not sufficiently bad. By having this debate we've already implicitly accepted their premise that something bad is going on.