Since X Factor USA been axed, Mr Syco has no other place on US TV to go apart from Amerocan Idol (which he won't) and since Howard Stern stated that this would likely be his last series of AGT would it make sense for Simon to join the show? Remember Piers did both shows so its possible for Simon to do both

I think he is, it wouldn't shock me

he wants some onscreen presence here in the states

AGT has a solid following so I could see him being a judge for that. There's always plenty of singers too which is what really interests him.

The reason why Simon did not do America's Got Talent was because he had an exclusivity contract with Fox and America's Got Talent is on NBC. It is unknown if he is still under this contract.