I can see why people thoght this was a turn to the dark side for Lex. It wasn't *Chloe* who was hurt--it was Gabe. And from what the show has shown us, Gabe has been very supportive of Lex. He was the one who really seemed to back Lex when Lex was trying to save the fertilizer plant, sending him that email supporting him, and standing by Lex 100%, even staying with LexCorp when others seemed to be bailing (the beginning of last season.)
So, while I understand that Lex couldn't exactly fight his father on this because he wants Lionel to have the impression that Lex is weak, I can see where people would see this as a major turning point to the dark side, especially if Lex doesn't demonstrate any twinges of regret over stabbing someone in the back after they've been loyal to him. I certainly have a hard time buying that Lex suddenly believes Gabe was trashing him behind his back, given that Gabe has been loyal to him in the past.
Of course, this raises another question. If Gabe no longer works for LuthorCorp, how in the hell are they explaining Chloe remaining in Smallville? Remember, when the plant was going to close, before Lex came up with his plan, Gabe was planning to move the Sullivans back to Metropolis. So what's so different now? I could buy the explanation that Lex secretly pulled some strings and got Gabe a new job in Smallville (which would, to me, express that he felt bad for hanging Gabe out to dry)but I doubt the show will ever address this issue again.
Other than that, it was an OK episode. Although the FOTW was the dumbest thing I've ever seen. They couldn't give him a mutation that, you know, made sense?
Oh, and why is Chloe so pissy about losing her column? If I remember correctly, a few weeks back she said she was planning to quit. And I'd certainly think that she'd be glad to end at least one of her entanglements with Lionel. The continuity in this episode was lacking in some points.