I'm always happy to see bug fix releases! Given the size and age of Logic, it may very well be the case that the work involved in getting everything ready for ARM Macs was very considerable. We don't know and they won't say
Nothing against bug fixes, but again, does 10.6 do anything you can't do with the last 10.5 release? It requires a OS update (for me at least) that risks rendering other things obsolete, so updating is not exactly a no brainer.
Why not just follow Apple's recommendation, create a backup of the version of Logic you're working with right now (presumably in your case 10.5.1) then update, if you want to go back you can. If you don't want to update your OS (I see you are still on Mojave, maybe you don't want to "burn your 32 bit bridges" by going to Catalina) you can clone your system to another external drive and update that, at least to test whether 10.6 is good for you. Works for me, I have on various systems Logic 10.6.2, 10.6.1, 10.6.0, 10.5.1, 10.4.8, 9.1.8 and 7.2.3 all installed and available if necessary