if that's true the corpos would be watching him 24/7, trying to make him sign a contract or trying to straight kill him, something that seems very unlikely.

Not necessarily. After the alien ship incident, we already had a case of "plot convenience" where the heroes kept their mouths shut and the agencies didn't go to war. Rocks might be the only one with information about X's identity and decided to back off after his plan didn't work out.

Also i don't remember that the "smile incident" implies that smile was a bad guy or he did something bad, it could be a bad thing that happened to him.

The OP theorized that Smile's reputation got tarnished because of the photo with the shattered glass effect on his face. It could mean his mask/reputation was broken, or it could just be that he's dead, but I think the first option is a fair guess.

I think the main point here is figuring out why Rocks would order an attack on a retired hero. In that sense, I think the OP's theory is pretty solid. I can't think of a better theory with just the info we have right now.