See discussion in Q56: Herald "Commit hooks" are being run even for commits that won't be published, which is confusing.
Technically, that's because "commit hooks" aren't actually Herald rules - they share UI, but are implemented in a different place..
I'm not, personally, 100% convinced that the hooks should be blocked from running on these refs - there's plenty of edge-cases where this might be even more confusing (commits can become published in a bunch of ways).
But in any case, we need to come up with a non-confusing solution to this situation.
Just trying to convince you.
If the feature works, it adds functionality that can't be easily replicated. You can have a bunch of complex Herald rules and bypass them all just by declaring that ^temp/ refs are now non-permanent. If the feature doesn't work (or maybe doesn't exist, rather), you have to go to each Herald rule and explicitly exclude ^temp/ branches, which is a lot of work for something that (at least for me) looks like it should be simple.