But were they any worse than Obama or Biden who repeatedly called Trump an existential threat to democracy ?
Yes. Calling Trump what he is is an inducement to VOTE, not to violence. Some loner manchild in rural America going crazy when there is a large rally nearby where they can suicide dramatically is not someone who is responding to a threat to democracy - it is someone responding to their own broken brain chemistry.
Those of us who respond to threats to democracy know that the best way to protect it is to ensure the vote for everyone in our community and ensure accurate information for every citizen. Democracies die from lies, propaganda, greed and corruption - you dont defeat those with bullets. In fact the bullet that grazed Trumps ear just made an enriched growth medium for lies, propaganda, and corruption.