Whilst it may have been a throw away line, the Dems have made it clear that is how they view Trump supporters. Their rhetoric does not show any distinction between a small group of extremists and the many millions of normal, decent Americans who wanted Trump as their president.
Instead they are fanning the flames of hatred by trying to impeach Trump, especially when they only have circumstantial evidence, hurriedly undoing anything he did and deny him presidential entitlements (access to briefings, presidential library). For a diehard Trump supporter, I imagine it feels like the Dems have spat in their face whilst dancing on their captain's grave.
If this were a battle to win hearts and minds, such tactics would be considered woeful. How can the Democrats not see the consequences of their actions? They will only fuel resentment and further division.
Btw the modern day Texas secession movement has been around since the 90s.