I don't think Aaron really needs any loyalty from Anton. The show's over, Aaron won, both are moving on with their lives. If they want to be friendly with each other, why not? It's not like Anton is going to sabotage Aaron and Faye in real life - that was all for TV (part of his "game plan", if you will).
I always enjoyed the Aaron-Anton feud. As much as I hated Anton, I was glad when he stayed over Aden, only because it meant more of the amusing Anton vs. Aaron warfare.
Anton provided Aaron with some of his best material, and Aaron seems to understand and appreciate that in retrospect.
I'm still not going to buy Anton's single, I think it's crap, but I do think it's nice of Aaron to promote it for him.