"it depends" is the closest you come to the truth in that whole rant. The trouble is that "it depends" on too much, to be really /sure/ you have to do far too much work for it to be practical.
A bug is an unexpected behaviour, and because we're talking about the kernel there is no safety net. Unexpected behaviours have security implications. Sometimes very obvious "ordinary users can overwrite any file" and sometimes more subtle e.g. a race condition which sometimes leaks an fd into a child process that shouldn't have it and often far too subtle to describe in this small text box. You can only analyse those implications in a given context. What seems like "no security impact whatsoever" to you may be a huge problem for somebody else.
Since kernels don't have "just one bug" the analysis becomes even more difficult. Maybe a particular bug just makes it possible to force a particular kernel function to run a little slowly, maybe it takes 500x longer than usual. No security impact? And maybe another bug causes a race condition, where it seems that the winner will always be the safe choice, because the other side of the race is too hard. And you combine them, and suddenly you can reliably win the race.
Whose job will it be to explain to a user how the first bug has "no security impact" although without it nobody would have broken into their machines and cost them millions of dollars?
Your "blue sky" argument isn't a blue sky argument at all, but a simple straw man. You're claiming that people always operate the open world assumption, which is a laughable supposition. But worse, you try to equate caution (not claiming to know whether bugs have a security impact for the user) with something quite opposite (claiming to know that no bugs have a security impact).
BUT you can prove me wrong on my main point. Just provide a detailed commentary for a few months of all the bug fixes, stating categorically whether they do or don't have security implications. If you can do this reliably you'll silence me because you'll have proof by example, rather than just a lot of ranting in forums.