turning point where no credible Democrat could argue that Biden was not competent to be president.

Despite all of the evidence before that time, it was at that point that all Dems knew Biden wasn't competent. It was at that point that even they realized that unelected people were running the country....and they didn't care!
It was "party over country" for the Dems (as it still is). Despite all of the sacrifices that our military veterans have made over the centuries to ensure our democracy and self rule, they (and most definitely you conor) were willing to throw away self governance for the sake of your own selfish agenda.