Maybe he wanted more money. Maybe Mutoh doesn't think he's worth the money he was making. Maybe they're just going in another direction. Maybe they're building him up to come back. Maybe A-Train just took his spot. Who knows. The only guys in AJ who actually have contracts are Mutoh, Kojima and Hayashi, so anyone else can come and go pretty much at Mutoh's whim.
It's the first I've heard of it. Mutoh, Hayashi and Kojima are technically under contract to LEGLOCK, but with Mutoh in charge of AJ, it amounts to the same thing. It would make sense, and I'd at least have Kea, Honma and Suwama under deals, but I was under the impression everyone there was working without a contract.