I could also see that happening, but it'll probably depend on how their reunion goes. Either Atlas will realize that Cas was a whole lot more capable than he ever gave him credit for and loosen his leash, or he'll claim that Cas is only in love with Iris because he has Stockholm Syndrome and needs to stay away from her to undo the brainwashing. I'll decide later after we see more of how he behaves while he still thinks his son is dead