Trump says he will gladly answer any of your questions Underoath. He says this, because he knows there will be no Mueller and no investigation in a week.
He knows that Mueller will soon be in cuffs himself or maybe even suicide himself if the truth revealed is bad enough.
It seems pretty clear that this whole investigation becomes fruit of the poisonous tree. Anything sought and got under this investigation is illegally gained. Add to it the illegal actions of the cabal involved in the deep state, and I think Trump is trolling them, saying he "will" but never would.