That doesn't seem a good analogy to me. Biden holds two positions: a moral objection to abortion, and a belief in personal choice. In this case he allows the latter to trump the former. There's nothing contradictory or hypocritical there - we all make those kinds of moral trade-offs all the time.

I don't see how this is analogous to the case of a campaigner for trans rights who is attracted to a trans person to the point of making out with them, but is then repulsed on discovering they are trans. There's no conflict of moral principle there at all - just transphobic hypocrisy.