Neither of those guys were going anywhere other than where they signed. McMillian for whatever reason fell in love with tOSU and Chubb was always coming to UGA. I don't know much about McMillian's recruitment, just he never showed much interest in anyone other than tOSU, Chubb on the other hand was paying a courtsey visit because USC had recruited him so hard and then SOS wasn't in town. Any article that tells you different about either has some incorrect information.
Xavier Thomas was pretty close to being a Gamecock lock. That didn't stop the Clemson staff. No article knows for sure what a recruit is going to do.
In XT's situation, something suspicious happened between the weekend of the spring game and his Clemson visit. So it may be an outlier. But my point still stands neither you nor your insiders know for certain what a recruit is going to do.