Subject: Re: what if...
Does not the law apply to everyone, no matter who they are (except diplomats)?

The law does apply to everyone. But all the law. The Supremacy Clause is part of the law, too - and it applies to this particular (weird) scenario just as much as Georgia criminal law.

I think the Constitution would certainly be interpreted that the State of Georgia lacks the power to prevent the President from discharging his office. What that means in this context is a very interesting question - I think the likely outcome is that if he is given a prison sentence, it would not start until after his term of office.

BTW, that is not unheard of. When there are pressing circumstances, you'll see a prison sentence be deferred until some time in the future. For example, if a pair of parents with minor children are both convicted of a crime, one parent might have a reporting date after the other's release so that there's always a parent home for the kids.