Guinness:
The only thing he was charged with, among those, is “refusing to allow his people to testify”, the technical term for which is “invoking executive privilege”, which he is allowed to do. Congress then has the option of going to court, which they declined to do because were in too much of a hurry to actually do their job.
@Guinness, Trump did not invoke Executive Privilege. He is asserting that Mulvaney and others have “absolute immunity” and don’t need to testify.
This is not a thing in impeachments.
Mulvaney, as an example, is simply not complying with a congressional subpoena because his boss told him not to because,
one can conjecture, he knows that Trump committed impeachable acts.