That's called "speaking one's own mind" as opposed to corporate doublespeak devoid of any meaningul sense, so common in corporate meeting rooms.
The beauty of not being paid for what you do is the luxury of being able not to bother with bullshit.
And yes, security is overrated. All major "security" problems have always been DOS attacks that have NOTHING to do with "breaking" into anything. The biggest problem with computer "security" is the widespread adoption of "anti-virus" softwares. That plague does more harm than viruses themselves.
(Do you think soldiers, chefs, car salespeople, and senators talk especially differently, when they're not in the limelight?)
If anything, this little statement has entirely too few four-letter words to be a really believeable engineer rant.
Of course, if you want to see someone as immature it always helps to rip a single statement entirely out of its conversational context. I frankly have no idea whether Torvalds is being sensible or stupid, brilliant or childish here. It depends on who is asking what.