That's a good point, Isaac. Select into, security label, comment, etc are all maintenance style commands but are already added to the matrix. I do think there's a good case to include other maintenance related commands as event triggers. Suppose you want to know the last time a table was vacuumed or the last time a table was reindexed. If you can trigger off of these maintenance commands, there's a lot you could build on top of postgres to make the maintenance experience easier. Seems like a positive thing.
The code exists but they are disabled at the moment. Happy to enable those with a patch if it's as Aleksander said. Meaning, no real reason they were disabled other than someone thought folks wouldn't need them.