My future daughter-in-law (my son's fiance) is transgender.
She doesn't announce this in-game (why would she) but if someone starts making slurs against the trans community she simply mutes and reports. Then again, she's very comfortable with herself and doesn't get easily offended by trollish behavior - especially online.
Which, ideally, is what you should have done in this situation. Then you'd still have your account.
That being said, sometimes you DO need to take a stand, even if it costs you something personal. Like a league account. Which is not tangible thing, and ultimatel in the scheme of life isn't really that important. Did the teammate need you to stand for him or her? Who knows. But, maybe they DID and maybe your actions helped them just a little bit. Sure, it might have cost you to fight back (people have been jailed, fined, and executed for less) but maybe in this instance you did the noble thing.
No good deed goes unpunished, as they say. The stoic thing to do is take your lumps. I hope it was worth it (i really do, I'm not being snarky). Sometimes we make sacrifices, or do the 'wrong' thing for the right reasons.
I don't agree with your decision, but I salute your reasons.
[slayer-jinx-catface]
Lastly - lest some fool claim I'm some "SJW snowflake" (or whatever the lastest insult is) - know that I'm pretty dead center on the political spectrum (with slight conservative leanings fiscally and slight liberal leanings societally) and am obviously an 'old fart' who is sick of humanity's BS. We treat each other terribly sometimes, for really awful reasons. I find the rage on both sides of the political aisle both distasteful and dishonest. Not that it matters. But seriously, just be your own person, I say. If other's don't like it, find new 'others'. Ultimately, as was suggested in Bill & Tedd, should we not be 'excellent to each other'?
Peace.
(And not that it's anyone's business, but I'm proud to say that my future daughter in law is the best thing that has ever happened to my son. She's helped him become a responsible adult. We once told him if they break up, we'll adopt her and miss HIM... should have seen his face, LOL)