I would admit to it being illogical, in that I didn't use logic to arrive at that statement. But it's an entirely rational statement: I arrived there via pattern matching, though, and not logic. Is it irrational when I look at a face and recognize it? If not, then why so with other patterns I recognize?
And it's not a conclusion at all; it's just an observation. People who are as obviously disgruntled as the employee in question often end up striking out. Some, a very few, strike out violently.
The employee in question has already shown evidence of "striking out," he just hasn't escalated past passive-aggressive behavior. I used an extreme example of striking out to throw it into perspective: He's not happy, and he's willing to do things out of spite, and that's a liability, even if he never ends up violent.
There are lots of scenarios that don't involve physical harm: Leaking confidential information. Cleverly hidden time-bombs in code that no one else understands. Lawsuits. Spreading discontent among employees.
Why? It made my point that he was dangerous, though to an unlikely extreme conclusion, which I admitted was unlikely before I even said it. I would hope everyone reading comments here would be perceptive enough to recognize hyperbole when they read it, especially since I called it out as an exaggeration. Given that no one is likely to take it literally, what is the problem? What is the real danger you're warning against?
Not sure what your goal with these comments is, honestly. Seems like I hit a sore spot, given the temperature of your replies. Apologies if I somehow hit close to home.