Under normal circumstances I would say any subpoena to testify before Congress should be honored. But these aren’t normal circumstances, are they? Calling Joe Biden or his son Hunter is beyond a political ploy. It is McConnell and the Republican controlled Senate furthering the same lying scam IMpotus was promoting that kicked this whole impeachment off. The question at hand is whether 45 abused his office by applying pressure to a leader of a foreign nation for personal political gain and did he withhold critical, already Congressionally appropriated funding to apply pressure to the Ukrainian President in order to try to force him to do the requested “favor”. The answer is clearly yes, and yes. (Particularly in light of the emails disclosed through the freedom of information act that show the freeze went into effect 90 minutes after the infamous call with Zelensky and the aid was only released 2 days after the whistleblower came forward.) But what would the Bidens know about any of this beyond what the rest of us know? Were they in the room? Have they had access to additional evidence regarding 45’s actions that the rest of us have not? Nope. This is just yet another attempt to sully the good name of one of IMpotus’ primary rivals. To subpoena Biden as a witness while refusing to call witnesses with actual information such as Mulvaney or Pompeo or Bolton is preposterous. So under the circumstances I do understand why Biden is not inclined to cooperate in the political attack against him. I can see how he would view doing so as not only a negative for himself personally but that it would also be a negative for the nation since it would place him in the position of playing along with the farce McConnell clearly intends to put forth in lieu of the actual serious trial this country deserves. If the identified purpose of the impeachment were to pass judgment on Biden’s suitability to serve then I would absolutely believe he should cooperate. But Joe Biden has nothing to do with the impeachment or the charges against 45. The Republicans just want to put him on trial instead of tRump as a distraction from the facts.