From many people's perspectives, it makes sense to take out Sophie. Jeremy and Michele especially. But does Tony's reasoning really make sense? His logic was that Sarah will come to him if he takes out Sophie. Does Sarah really seem like a player to take that easily? No, she's going to be furious with Tony. You even saw that in next week's previews. We've seen tension between Sarah and Tony already this season, and this will just add fuel to the fire.
Now, if Tony's reasoning is that Sophie and Sarah were running the game, and he wanted to take control... that's totally different. But that was not his reasoning. You can argue that his moved benefits Jeremy and Michele the most out of this, and I think that is hard to argue against. Jeremy and Michele could go so many ways now. They could get back with Kim and Denise. They could go with Sarah. They could go with Tony. I think Tony's move takes power away from him, Sarah, and Sophie, and puts it in the hands of people he hasn't worked with up until this point.
Again, it's not a numbers game as much as it used to be, but Tony really has no close ally anymore after blindsiding Sarah like that.