Let's break down the theory of JUST your original meme (no fair ad hominem attacks on Trump, you've already lost by doing that).
1. You say (to paraphrase) that Scalise was shot by a mentally ill person. Check for you, that's a given.
2. It is a fact that James Hodgkinson was a Democrat and a Bernie supporter. Check for me.
3. In the spirit of this being a humorous meme site, I took the association that you established about the mentally ill not being allowed to have firearms and extended it to its logical conclusion, Democrats and/or Bernie supporters which, if you'll remember from paragraph two, James Hodgkinson was all three (mental, Dem, Bernie boy).
http://www.nbcnews.com/news/us-news/james-t-hodgkinson-illinois-man-identified-suspected-gunman-virginia-shooting-n772271
