Also...sorry to be a downer in the middle of more interesting news...The truss rod notching and nitrocellulose sealant on the SLO's lovely Sonic Blue P-IV was likely one of the last ones done (the body from SLO's P-IV was completed last year), and YJ won't do them any more except for a surcharge.
In short... it somewhat has to to with him wanting to keep consistency on the used market, but more about him not wanting reluctant exceptions to be understood as standard options among potential buyers...since he's a busy guy who can only do so much as a solo builder, and the build list isn't getting any shorter. As folks already know, he's never been a custom builder with an option list that resembled anything like a diner's menu, and whenever possible he never intended to skew far from what he's already decided were already Leo & George's masterpieces, even when some elements maybe needed a little push.
As such, the truss notches began as compromises on behalf of a few partially-sponsored individuals, but he was never in favor of them, especially since he's always felt that neck adjustments should be done under no string tension and well off of the body regardless of the inconvenience. I for one have "worn in" makeshift notches in the bodies of mine that works just fine for me, and YJ has no issue with folks modifying theirs (as some have)...he'd just rather not do them in-shop.