Those 4 are merely liberal republicans holding (or were, or vying for) contestable seats where we can do better, seats that are in play in elections, the Kennedy seat is not.
Brown winning that permanently Democrat seat was a fluke and a lucky break, either he stays in it or it reverts back to it's normal state, radically leftist.
The permanent Ted Kennedy seat is totally different than the 4 you mentioned, don't look a gift horse in the mouth.
Would I want Arlen Specter to win Teddy’s seat so he could poison the party from withing. No. RINOs are a cancer and eqally responsible for our predicament. The fool ain’t gettin a penny from me.