The products I knew, it was the macOS part that was weird to me. Either way, just wondered if there was a connection between to the later launch of macOS and a new MacBook Pro.
It is pretty common for the new MacOS and iOS to be previewed at WWDC with availability sometime in Sept/Oct/Nov. I don't recall them ever having an "event" to launch a new OS that had already been showcased at WWDC.
I don't recall any consistent synchronisation of new Mac and new OS releases, either. No True Scots... sorry, no sane "pro" user is going to install Catalina on their production machine on day one - aside from the trusty adage "don't buy version 1.0 of anything" there are always some key applications that don't get updated immediately - so it actually makes sense for new models to initially ship with the old OS. The 16" rumour doesn't sound like it includes any exotic new hardware that would only work with Catalina.
There was nothing surprising about this week's event - every year people get convinced that Apple are about to announce new Macs, iCars and Mr Fusion at the September event, then act all disappointed when its just a slightly upgraded iPhone.
The 16" MBP is still just a rumour - nobody here actually knows if it will launch this year or not... but bear in mind that (a) its getting on for 6 months since the last MBP update, (b) its 4 years since the last significant physical re-design, and (c) the recently updated "non-touchbar-MBP-now-with-touchbar" are a branding trainwreck* that shouldn't really be lumped together with the other MBPs. So a new MBP in October wouldn't be that
premature, especially since Apple desperately need at least one laptop that doesn't have the discredited butterfly keyboard.
(* I'm talking about branding here, not the hardware - they have lower-powered processors and fewer ports than the other MBPs but there's no sensible branding to differentiate them. Problem goes away if the "real" MBPs morph into "14" MBPs". Personally, I think they should be re-branded "MacBook" now that the 12" MacBook-should-have-been-Air is dead.)