Menu's can already be easily extended directly it seems?

Found this code comment from David when he made the data table view's All menu extensible. There's a loop to call all the extenders.

But is this extensibility only for the All menu directly?
Or is there handling to extend easily for any menu in the DataTableView (thinking to make it even easier for extensions - and what we could do here - perhaps just a few better code comments and docs updated)?