"I'm a girl and I'm a runner" ...
this quote is correct.
Nobody is saying she shouldn't live her life as a woman / be a woman/ become a woman or whatever the appropriate phrase is.
Nobody is saying she can't be a runner.
What I'm saying is a trans MtF girl who is a runner (or any kind of athlete) isn't a GIRL RUNNER. Live your identity. Compete as your biology dictates.