This is the only screenshot that the researcher posts as 'evidence' of gaining access to Trump's account. I'm afraid that this one can be easily faked with browser tools. The fact that White house officials have extra security measures on their accounts it is this only screenshot that makes it less convincing that this is true, unless the researcher publishes multiple screenshots or video evidence of logging into the account themselves.

Otherwise it can be easily dismissed as a fake screenshot, even if he 'did it' in the past.