Doesn’t make you a leftist. The two people who tried to kill Donald Trump were clearly not leftists.
> He inscribed "anti-fascist" slogans on the bullet cases, like "Hey fascist! Catch!" and "Bella Ciao" (which is used by Antifa organizations);
“Antifa organizations”? Additionally, the first is a reference to Helldivers which he also referenced on another bullet casing, which you omitted.
> He texted his roommate “I had enough of his hatred. Some hate can’t be negotiated out.” in reference to Charlie Kirk;
Complicated statement using language the left sometimes uses, I can see what you mean on some level. However, I absolutely find it objectionable to claim that wanting to kill people over speech is somehow a leftist ideal.
> He was dating a transgender person, and had multiple references to the "furry" subculture.
Last I heard that was none of that is as clear cut as some outlets made it out to be, but let’s assume it’s all true: Conservatives can’t date people who are transgender/can’t participate in furry culture? That is a completely unfounded generalization and some cursory research will show you that not every conservative is a cishet dude. Also, what on earth does dating somebody who is transgender (or his maybe being a furry) have anything to do with this? You’re falling into the trap of conservative politicians trying to link everything bad in this country to the transgender community.
There is no doubt he held ideas that are of the left, but he is clearly a very complicated person. I would say he probably leans more left that he does right, but he is not “a leftist.“ The entire point of this discussion is that people are being way too myopic in their thinking. It’s easy to slot people into a neat binary when we are ranting and raving against caricatures of people who we disagree with. It’s different when we actually encounter them in real life.