Is this story corroborated?
If not, then it’s just more fake news from never-Trumper Glenn Beck.
Presidential “flunkies” do advance work to make sure nothing at a locale will embarrass their man. Probably someone saw the McCain and figured it wouldn’t be good to have it in a picture with Trump, so he asked it be moved.
Presidents usually don’t know about these things, they don’t pay that kind of attention to minor details on their trips, and the flunkies involved probably don’t have the experience and maturity to handle such matters.
A tempest in a teapot.