We’re seeing a pattern to how Democrats respond to election losses: do an end-run around democracy. You can’t block a union bill? Flee the chambers. You can’t repeal DOMA? Declare orientation a protected class all on your own. This tactic may backfire, however: It opens up the pathway for the House to intervene to defend the law.
This also shows how much they don’t believe they have the Supreme Court votes to win yet.