While I will allow as to how having the thought is not the same as doing the deed--I'd be locked away for multiple counts of all kinds of crimes were that so, with how often it crosses my mind to kill or rob someone--there is a hard limit which comes when the person who has the thoughts knowingly (even intentionally) takes a job that makes victim access not only likely, but guaranteed because it's a part of the job. At that point, it doesn't matter if he's non-offending or not. He knows his inclinations and he's deliberately putting himself into a position where the opportunity to act on them is available to him.

If the hypothetical were different, if it involved someone admitting that they'd like to shoot up their workplace, maybe specifically target people who are black, or women, or what-have-you, I'll bet that not a single of these comments would be "oh, but it's just a thought, he hasn't acted on it, it'll be fine."