Couple of things going on there.
1. Often the people doing that kind of "considering" are... how shall I put this... not the *nice* feminists. Not the people who are trying to legitimately seek fixes for real problems, or genuinely help the world become a better place. Instead, they're the ones who are so wrapped up in their own little soap boxes that they are almost incapable of seeing anything outside of their own little ideological bubble, or the ones who legitimately hate (or, at least, dislike or harbor ill feelings towards) men, or the like. Sometimes feminists like that are the *loudest* ones, but that doesn't necessarily mean they're anything even remotely close to a majority of feminists.
2. Some times, those people...do not act like people who are "consistent against injustice", but more like people who are, eg, trying to score points against the feminists. Like, if a feminist brings up some way that women are treated badly, their first response is to try to derail the conversation onto some (maybe related, maybe unrelated) way that men are doing badly. That kind of thing happens the other way, too (ie feminists derailing a legitimate discussion of men's issues to bring up women's issues instead), but anyone who's doing it in either direction is not acting like they are "consistent against injustice".
And probably more reasons I could think of if I wasn't up about 6 hours past my bedtime.