It is literally part of Beehaw rules to be nice to each others, cf this excerpt from beehaw rules:

If you aren’t nice, we’ll remind you to be nice. If you continue to be problematic, we’ll escalate from there, but it will be on a case-by-case basis. If your first reply when we ask you to be nice to each other is to tell us to “fuck off”, we will respond in kind.

It is also part of the rules to not be transphobic, cf

we simply do not tolerate intolerant behavior. Being explicitly racist, sexist, homophobic, transphobic, or bigoted in any other fashion is not tolerated here.

If you find a transphobic post and you feel that you are unable to reply nicely, the correct course of action would be to report said transphobic post.

If you are not content with this rule of "be nice" I'm afraid Beehaw is not for you