Robert Bowers is anti-Jewish. He is not pro-Trump. He in not affiliated with either party. Being anti-Jewish is not an exclusively far right position. Most of Israel's neighbors don't like their Jewish neighbors either. Using the anti-gun narrative would probably be a better spin than trying to link Robert Bowers with Trump in this case.

https://heavy.com/news/2018/10/rober...ican-democrat/

"Bowers was critical of President Trump on social media, according to Heavy, saying, “For the record, I did not vote for him nor have I owned, worn or even touched a maga hat.” two days before the attack, Bowers wrote, according to The New York Times, adding: “Trump is a globalist, not a nationalist."