>What did he mean by this?
I could be totally off base, but this sounds like he knew there'd eventually be a sham committee (or even a fair one) in which this person (the "lawyer") would eventually have to give "testimony" at – revealing the inner secrets of foreign policy or other important matters.
Sounds to me that PDJT avoided having those sorts of conversations with certain individuals knowing they'd eventually get put on the chopping block in a kangaroo show trial.
Either that, or me needs more covfefe.