What reason is there to believe she would have voted for a conservative justice? A backstaber who pays the price might give the other backstabbing RINOs something to worry about.
Mainly that the earth has shifted under her feet. And by the force of this logic:
(1) Trump made it very clear in his campaign that he would be appointing conservative justices, like the late Justice Scalia.
(2) Trump won a convincing election.
(3) Therefore it is the will of the people that the Senate confirm a strongly conservative nominee, like Justice Scalia.
I think the Olympia Snowes and Susan Collinses of this world tried to justify their rogue behavior by pretending that conservative nominees were "out of the mainstream" of American opinion. Now it is clear they don't have that excuse any longer.