I have to disagree vigorously with you.
This is not tacky, this is dangerous. And this is not done by both sides.
Charlton Heston was not a former President of The United States. Obama is.
And the fact that he grinningly went along with this is something that people should sit up and take notice of.
Any American former President should have said after that introduction “I am not the President. Donald Trump is the elected President...”
But he didn’t. That is what I would have expected a former American President who believed in the Constitution to say.