Kind of like how Biden and Hillary both caved on the war?
Politicians are politicians.
I think your labeling of Biden as "sexist" because he was on the Judiciary Committee trying to uphold some semblance of decorum in the Senate and keep the Democratic Party from tearing apart during the time of Thomas' confirmation is weak at best.
Obama had 8 supporters on the committee, the second largest bloc other than Senator Clinton's plurality.
After weighing the support for a 50-50 delegate allocation among the undecideds and Clinton supporters, the Obama campaign - through David Bonior - instructed their supporters to back the MDP proposal and publicly accepted this result.