Technically, you're right. Today, any junior employee that made a joke like that would be crucified and practically blacklisted from the industry. What you should be thinking, however, is not "why does Linus get away with saying things like that?" but rather "why do I consider it normal for someone's livelihood to be permanently destroyed over a stupid joke?"
The appropriate response is to immediately start thinking why you need to figure out a response to any low-quality joke people make. Maybe, just maybe, there is absolutely no need to make any response whatever. Think about it.
I think if people would stop pretending to be offended by ridiculous things, the problem would solve itself and we wouldn't need to have a "response" in the first place.
That's the idea. Any developer or researcher who uses obscure or meaningless names like "P" and "V" needs to be publicly shamed for it, no matter how well-respected they are. Clarity is vital in this business.
