This amendment makes no sense to me.
It's a great way of saying "I've done shit but fuck you".
Theres two aspects to it. In the one hand, they cant force you to say stuff thats only going to get you in trouble.
On the other hand, you dont get to offer any sort of defense for yourself.
Here is a picture of Carter Page meeting with known Russian operatives. You dont get to make he admit he met with them, but he also doesnt get a chance to say we were just there for intercourse. Nothing political.
Typically people plead the fifth as a way to not have to rat out a higher up. Hilariously, it practically never accomplishes much outside of dragging stuff out.
Hes still going to go to jail. It will just be because of someone else.
Edit - Im also not sure he can refuse a subpoena on the grounds of the fifth amendment. You can refuse to answer specific questions as they relate to you, but if they ask did person a meet with person b, as neither of those people you cant plead the fifth.