That's pretty much what I had in mind. In retrospect, I don't think I ever actually bothered zeroing the BUIS; I had the plastic placeholders on until the RM06 was installed and dropped on suppressor sights afterwards, aligning them to the dot. I'll verify zero with the RMR off next outing. I might just be overthinking it; there's a part of me that's been saying "just zero the RMR so you're hitting dead on and move on," but I always worried it was a band-aid solution for a user-induced issue. These days it's a bit of that and a bit of "what if this is actually a mechanical problem with the gun?", but I guess if I'm shooting other Glocks fine there's no harm in adjusting the sights to accomodate this one's quirks.
That said, I'll still probably pick up a locking block at some point to try out and just to have as a spare. Still very curious as to whether or not a light striker safety will improve the feel of the takeup and make it more akin to the Gen 5 as well, but I'm having trouble finding anything really conclusive on that front.