I found myself offering advice again. might as well post it here:

Do I need to somehow prove my allied nature?

yes. post your opinions consistently and back them up with facts. The better sourced those facts are, the better.

Even if you disagree with the mission of the subreddit, presenting well sourced, well documented facts is a respectful and respectable thing to do.

Even if you're a true believer in 'everything mensrights', presenting biased opinions that have no basis in fact won't get you respect. Some might like you, but you still will have offered nothing of substance.