Either the Democrats are that foolish, or they are super-geniuses.
With the race this close they might deem it wiser to lose the battle to win the war.
If they lose in Mass, and Scott Brown blocks Obamacare, it may ultimately allow them to protect their precious majorities.
With some clever campaigning in the fall, coupled with the amnesia caused by Obamacare NOT passing, they may not only retain majorities, they may get back the magical 40th vote in the Senate.
The masses, after all, tend to get amnesia, even after near misses.