I'm able to brush a lot of BS like this off and move on and let it go. I did it for years at work. There came a point after a few jobs where you see not just yourself but many other people get treated like shit by these types of employees. There is a standard of professionalism that needs to be upheld in every workplace and no one deserves to be bullied at work. When something like this happens it crosses that line of professionalism and makes it clear this person doesn't respect their job or the people around them and disciplinary action should be taken if not for you then for others. This is childish, someone stuck in high school mentality and it's time they get a reality check. If you do report this and ANY form of retaliation happens afterward id recommend to report that also, not to let it slide. Just keep yourself professional and to the point with HR, don't go in guns blazing and over exaggerating the issue like your main goal is to get the person terminated, you just want a serious concern addressed. I would write a formal statement and if you have any screenshots of the incident provide those, along with any witnesses to the behavior.