It's most certainly not treason.
It is, however, playing with fire.
The right/traditional/patriotic wing in this country has been
generally law abiding and going through the political process in the traditional way.
People have limits, though. Trump is a result of the blue-collar workers feeling generally ignored and put upon. (Which they rightfully feel, even if they are looking to the wrong person to fix it.)
Try to stop the legitimate expression of their frustrations with violence or the threat of violence? The sucker punch in North Carolina is just a hint of what will result.
Please note, I'm not encouraging the resulting violence nor am I pleased by that outcome. I'm just predicting it, given what I know of human nature.