All Rock can do is lame childish shit. Cody already no sold the chicken nuggets stuff and Seth is obviously fruity anyway so any insult about that part of his gimmick fails. What more can Rock say? More stuff about putting things up asses? If he tries to talk about the Rhodes' at all Cody can fire back about all the shady shit Rock's family has done. Even if Rock could go all out like he used to, the times have changed too much.
Also, this should go without saying, Rock is full corporate sterile Hollywood golem now. He can't mock people on their race, sexuality, politics etc. because he is gearing up for a Presidential bid in the next season or the one after. Its the reason he did that whole twitter post; "he was actually playing the heel, which is wrestling lingo for bad guy haha."