It looks to me like MA 11 closes completely to all salmon fishing, whether boat or shore bound on Sept 30th.
The not allowing fishing from a boat seems to be a new management tactic WDFW started using a few years ago. They did it in MA 9 as well.

I don't have a boat and fish strictly off shore, but I feel for those that have boats and can't use them to fish out of.
I'd guess their reasoning is boats are more successful and you'll have less encounters with whatever species or whoever's interests they are trying to protect.

I've had some great October coho days in both MA 9 and 11, but those days seem to be a thing of the past.
SF