The facts they can't refute are:
1. Idiot boy was only on Burisma's board for access to Joke
2. Joke threatened (extorted) Ukraine if they didn't fire Shokin because he was corrupt
3. Shokin wasn't corrupt
4. Shokin was investigating Burisma
5. Burisma is (or at least was, at the time) corrupt
If a proven money-launderer setup a bank account for idiot boy in another country, it's merely another piece of the known puzzle.