I don't think Tom would have given her the immunity necklace under any circumstances. Tom knows that he is the strongest player in the game and thus is a primary target for getting voted off. He wouldn't risk being voted off just to let Stephenie stay. I would love to see a Tom vs. Stephenie final because they are both strong competitors. I also like Ian, but I fear that he's a little too nice to make it past the final four.
I liked Tom up until last night's episode. He caved in and was going to vote Stephanie out. He practically said so when Jeff asked him if Stephanie was the type he would want on his team as a co-worker. He said yes for work, but this is a game.... Steph owes him nothing now. Game on.
One more thing about Steph. Her living is made in the sales/marketing arena. She knows how to overcome "people" obstacles and she will play the game wisely. She is a fighter. Go Steph.