True, she never actually gets to stand up and say “I’m bisexual” (annoyingly) but River didn’t either…
That’s queerbaiting, not canon bisexuality.
River literally said she married (at least) two women in her life, which is rather different.
I disagree in almost every way, but I can’t really articulate it, other than “Is there really that much difference between River casually saying she married a woman and Clara casually saying she kissed and loved* one?”
*Loved! This is the first time since Danny she’s said that about anyone!