I disagree. Biology is empirical, objective, and applies the same to all humans. The same can't be said for gender
No; only gender means different things to different people. When somebody says they are a biological male, they are saying they are XY, they have a prostate instead of a Uterus, testies instead of ovaries, a testosterone level of somewhere between 900-1200 instead of 15-20, etc. etc. I could go on but I think you get the point; when people use biology they are being consistent with what they mean.