It wouldn't do him any good to join the minority. He benefits by being in the majority.
When Jeffords tipped the majority to the Dems he got keep his chairmanships and got other perks. Now he has nothing.
Not in this session. But potentially he could do it in the future if there were a slimmer Republican majority. The longer we coddle him, the more dangerous he'll get. I'd rather eliminate him in the next election.
Better to dump him in the next election, and pick up some Republican seats in the process. Even if he jumps on Monday, the Republicans still hold on to the Senate.