we should keep assuming that the attack was left wing in nature

That's your own conjecture and I'd ask you to follow your own advice. Not all trans people are leftist and not every act of violence carried out by someone with left-leaning politics is politically motivated, nor is there evidence that it had anything to do with him being trans.

I don't think it's really that conspiratorial to ask questions and verify details about the case, especially when there have been false reports of shooters being trans in the past. I do think it's reasonable to accept that he was trans but the LinkedIn profile isn't all that definitive imo.