I agree with your conclusion but think of the big picture here. Berniebots are the hardest of hardcore progressives and the backbone of Democrat voting. If their support of Biden versus President Trump is eroding, what does that say about the more moderate Democrats? The polls showing a lack of enthusiasm for Biden among Democrats suggest that his support is eroding in this larger group, too.
The Democrats in Congress have behaved horribly in this crisis, but then what could we have expected? Politics takes no break with them! As an ex-RAT myself I hope people on that side of the aisle are waking up to the reality of what their party truly represents and they begin to realize, as I and many others have, they don’t have the best intentions for the country!