Would such written testimony be under the equivalent of an oath? I would assume that his attorneys would negotiate to make any such submission not subject to penalty of perjury. In any case, the chances of Unser Drumpfenfuhrer actually doing this are lower than his, inter alia:
When we’re all slaving away in the Koch mines in the fifth term of God-Empress Nikki Haley of Karl Rove’s Perpetual Republican Majority, I will take one moment to wipe the sweat from my brow (just one, lest the whips come out) and exclaim, “Well, times are hard, but at least the President can string words together like a fucking adult”
Good lord, just read that tweet and then remind yourself that this is the President of the United States speaking. Un-f’ing-believable. This is Idiocracy-level behavior. Second-grade level insults. We have fallen so far, but have become numb to it.
I think his people would dart him like a rhino to keep him from going over there and testifying. He’s literally crazy to consider it for a moment. But who don’t know that?