I’m not a lawyer, but I’m pretty sure Biden cannot hide behind executive privilege if he’s questioned about his own statements that are now in the public domain because they’ve been posted all over the internet for months.
Biden is just a private citizen with no privilege so he has to appear before the Senate or he can be arrested just like any other witness. The problem is if he is forced to appear his lawyers must advise him to refuse to testify based on his 5th amendment right against self incrimination. He would be within his rights but from a political perspective it would be the end of his run for President.
Fortunately for him the Senate is prepared to bail him out and not have him testify. The Dems pulled the bribery charge which eliminates anything to do with the phone call from consideration. The abuse of power will only be about delaying the aid for personal reasons which is bunk. The obstruction of Congress charge is actually an abuse of power by the Congress for charging the President for resisting a demand by a coequal branch of government that he feels is acting unconstitutionally.
All of this avoids having anything about Hunter or Joe brought up so they can skate for now. The whole trial process is designed to be a “fast-track” way to dismiss the whole sorry episode so all the Senators can get make it to the Iowa caucuses in time.