He is incapable of telling the truth because he barely knows what it is. He can't make it through an interview because he'll make stuff up instead of saying "I don't know" or "I don't remember".

Just to gain bragging rights for a day.

It might knock a serious hole in the national debt. I know I’d pay to see him spin and lie to Mueller. He is so obvious when he lies. I would say we could make a drinking game out of it, but on second thought, I am not sure we want that many people taking a shot every time he says, “No collusion”. Or “Believe me.”

last I heard.

Sure RUMP...that'll work.

When a federal prosecutor offers an interview, the unspoken threat is that if the suspect doesn't agree to an interview, s/he will receive a subpoena to appear before a grand jury.

The Orange One's lawyers know that he cannot be questioned by any reasonably competent lawyer, much less someone from Mueller's team - he would hang himself. The lawyers will tell the Orange One that he must avoid an interview or subpoena at all costs. (I have some question that the Orange One is smart enough to listen to his lawyers. I can see him assuming he is smarter than the prosecutors.)

Mueller has to worry that if he subpoenas the Orange One for a grand jury, he will be fired - and all hell breaks loose.

It will be interesting to see how this works out but it could get ugly.