The “you’re full of $#!^” comment was more rational than most recognize: it was based on Biden believing that AR15s are _already_ illegal. He doesn’t want to “grab guns” which he believes are already banned (”grabbed”). Problem is they’re not banned, so the worker wasn’t “full of $#!^” after all.
Not having an accurate grasp of a contentious electoral issue is a bad position for a prospective president. Cursing at voters based on that misunderstanding is worse.
Biden taking the ‘Angry Joe’ or ‘Tough guy Joe’ approach is rallying Dems and some Never Trumpers who want to see Trump ‘beat like a drum’.
The fact that Trump picks on politicians and media types and Biden goes for the little guy to beat up verbally is lost on them.
All they see is their hatred of Trump.