I disagree. Biden could have and should have upheld the rule of law. This would've been difficult and emotionally challenging, but I think it was necessary given the position the left wants to take.
And yes, the word 'innocence' has two meanings and is broadly interpreted differently by those people who think about it. In this case, the people supporting Trump did not consider it an attack on Government, they saw it as a defence of Government from a corrupt election. They saw Trump as innocent - what was required was a long legal process to prove the house of cards defence on which Trump relied would be dismantled one assertion at a time.
You have eyes and ears, Republicans have eyes and ears. People hearing and seeing the same thing make different assertions and take different truths from what they saw. Asserting 'guilt' which you have inferred based on perhaps a biased decision is problematic, because it allows the 'it's a stitch up' defence. The correct response was to say 'he's innocent until we prove it otherwise' and then prove it a) as quickly as possible or b) outside of an election cycle.