Sometimes, complex situations don't have simple analogies. I'm not even sure mine is 100% correct.
Just like bumping into somebody on the roof is normal, but you should always be aware that there’s a chance they might try to throw you off. A researcher highlighting this fact by doing it isn’t helping, even if they mitigate their damage.
A much better way to show what they are attempting to is to review historic commits and try to find places where malicious code slipped through, and how the community responded. Or to solicit experimenters to follow normal processes on a fake code base for a few weeks.
Strangers submitting patches might be completely normal.
Malicious strangers trying to sneak vulnerabilities by submitting malicious patches devised to exploit the code review process is not normal. At all.
There are far more news reports of deranged people throwing strangers under traffic, subways, and trains, than there are reports of malicious actors trying to sneak vulnerable patches.
How could you possibly know that? In fact, I would suggest that you are completely and obviously wrong. Government intelligence agencies exist (among other things) and presumably engage in such behavior constantly. The reward for succeeding is far too high to assume that no one is trying.
Just because their actions didn’t cause damage doesn’t mean they weren’t negligent.