The biggest functional change is the way dependencies are handled for matview stats. Materialized views ordinarily end up in SECITON_PRE_DATA, but in some cases they can be postponed to SECTION_POST_DATA. You solved that by always putting the matview stats in SECTION_POST_DATA.
Accurate.
I took a different approach here and, when the matview is postponed, also postpone the matview stats. It's slightly more code, but it felt closer to the rest of the structure, where postponing is a special case (that we might be able to remove in the future).
+1. The fact that this quirk was a knock-on effect of the postponing-quirk, which could go away, makes this change compelling.