Watching this first the first time.

Yeah, at this point, the only reason Ranma hasn't revealed Ryoga's identity is because it's a running gag the author thinks they can just run into the ground indefinitely. There's absolutely zero logical reason why he shouldn't have done it by now.

Also, FFS, just give girl Ranma a different name and say it's your sister. It makes explaining to normies 100x easier.