Impeachment is not a criminal trial. The Judge (Roberts) can instruct the Jury (Senators) that they can assume that a 5th Amendment plea is an admission of guilt for the case at hand, just like civil court cases.
Once Hunter pleads the 5th, Trump has proven that there was corruption and he was justified in all of his actions. Joe’s candidacy for his party’s nomination is not a grant of immunity for his family. The DNC convention is July 13-16.
IMO ... I don’t believe the C.J. would instruct the Senators on how to interpret someone exercising his Constitutional Rights.
People will interpret his pleading the 5th based on whether they are for or against Trump. To expect to get blood out of a turnip... I wouldn’t expect Hunter to say a word.