By arguing "but Trump" you are telling us that you believe that Biden is as embarrassing like you believe Trump was.
Not what is being argued at all. Nobody is accepting that Biden is as bad as Trump, but I/we are stating that you are trying to imbibe Biden with qualities and acts that Trump has already shown in abundance. That is not acceptance of Biden showing those qualities, that is criticism of you for trying to make the equivalence.
EDIT - Trump surpasses (trumps?) Biden a hundred-fold in the 'national embarassment' stakes, even though I can't see what embarassment we can attribute to Biden. This is especially apparent to those outwith the USA, in all manner of ways;
the false claim of his inaugural crowd size,
the whiny drone of his malformed run-on sentences,
his ongoing obsession with low-flow toilets and other bathroom fittings,
his callous disregard for human life,
the nepotistic appointment of unqualified daughter and son-in-law to positions within the WH,
the blatant lack of desire to actually carry out the job he was elected to (evidenced, amongst other things, by 300+ days of his term spent at his own golf clubs, mostly on the course), and
his near-total disappearance from public view and presidential activity once he had been voted out.....
etc
etc