See and I wondered about this as well. Tommy is trying to make an alliance with Quinn, he knows about the drugs and the girls. Maybe he thought that Quinn would support him. I know Rusty doesn't associate with the drugs because he refused before the Cum-petition. It's feasible that Tommy could be thinking with Quinn's money and Rusty gone they could do/make more.
I might buy that since Tommy is clearly impulsive and (as we see in Episode 5) somewhat insulated from reality. I could see him biting the hand that feeds him without realizing he was doing that.
But Tommy also makes it very clear to Quinn during the flashback in Episode 4 that Rusty himself is a key to avoiding any scrutiny. So even if he didn't realize how much he needed Rusty's money, he knew how valuable Rusty's name was. There's no way he makes that boast about being a scapegoat to Quinn if he thought a simple cluck of Cathy could bring Rusty down.
Moreover, it sure seems as though Tommy still likes Rusty. He says in Ep 5 that he had considered Quinn an even closer friend, but I thought that was meant to showcase how close he was to Quinn, not indicate he had grown distant from Rusty. The disagreement over rebuilding the DIK house is the first real sign of daylight between them, and that is well after the cluck was posted.