I think whoever recieved this would be completely fine to report Linus to HR or something.
As unnecessary as the tone was, if your first reaction to such a form of address is to run to HR, you’re contributing to a toxic workplace. The first and foremost way to address etiquette problems (I am not including criminal behavior in this) is to talk directly to the person who offended you. Everyone has a bad day once in a while, and some people may even shout. If the first reaction is to get them into legal trouble with the employer, most people will rightfully avoid you like you just stepped into dogshit.
If this kind of behavior - despite having addressed it face to face - keeps occurring, that’s a different issue, then HR may be necessary.