So Biden could have blocked Trump in 2016?
Quite possible. As something that is not clearly defined the SCOTUS might have not knocked it down just like they might have if Pence had tried it. I know how much you love to laugh at the left's hypocrisy but the media was cheering the electors not to vote Trump in 2016. There was even a commercial with many actors pleading with the electors not to vote Trump. For some reason these people were not traitors or insurrectionists.
Here's the video. https://time.com/4603254/celebrities-electoral-college-donald-trump-video/