Note that precedent already set for “Impeachment of a former President” per Pelosi & Company impeachment of Trump over January 6 “Incitement”.

09FEB2021; “Article Of Impeachment Cites Trump's 'Incitement' Of Capitol Insurrection”: https://www.npr.org/sections/trump-impeachment-effort-live-updates/2021/01/11/955631105/impeachment-resolution-cites-trumps-incitement-of-capitol-insurrection

SCOTUS ruling indicates that Biden, Obama, Bush, and Clinton may be impeached and found guilty via Senate trial for official acts, and THEN prosecuted criminally (treason charges?). Anything proven to be “unofficial act” is fair game at anytime, and they likely are caught here as many things were done “off the books” and therefore UNOFFICIAL (such as selling weapons and secrets to our enemies). TREASON and UNOFFICIAL, both, imo, but lower court will define “unofficial” which might be very spicy.