You can, if you have a Supreme Court that is in your pocket and makes up new rules for the trial after the trial is over.
The SC ruled not only that Presidents have a presumption of immunity for Official Acts, but also that their aides in the Executive Branch can’t give testimony about things the President says or does, even if those things fall outside the penumbra of “Official Acts”. So, after the trial was conducted with rules that allowed a small amount of testimony from Trump allies who also happened to be part of the administration, the judge was forced to consider whether these new rules affected the case.