Scalia was unanimously approved and is widely regarded as a brilliant legal mind. You can disagree with his conservatism all you want but nobody disputes that he was a brilliant and well-qualified supreme court justice. His hearing was uniquely uncontroversial.
Biden voted against Thomas. His "vote for Thomas" was a procedural vote to send his case to the full Senate rather than blocking it in the judiciary committee.
Biden should have joined Paul Simon voted against advancing Thomas. He also should have allowed more witnesses to testify in support of Anita Hill. Like in his Iraq war hearings, he did a lot to advance the right-wing.
There would have been no point. Scalia advanced from the judicial committee 13-1. Back then, the judiciary committee was just supposed to be a round of preliminary questions by senators much more well-versed in judicial matters. Using the judicial committee to bar Scalia's nomination is the kind of anti-institutional move that would be commonplace in 2020 but simply wasn't done in the late-80s, and as a purely symbolic gesture, wouldn't have been in line with Biden's senatorial philosophy.
If you need any more proof, Biden had voted a few years earlier to advance Robert Bork out of the judicial committee, and he was one of the lead attack dogs who ultimately brought down Bork in the full senate.
FWIW, Biden voted to send Clarence Thomas to the senate floor
without a "favorable" recommendation. That was probably the more impactful vote, since the motion to label Thomas as "favorable" did in fact fail.
