No it says sharing is required. If you don't change the setting on your account then you simply can't access Fable, its not like the setting is ignored. I just tried this on my account and it blocks API requests to Fable.

Interesting. When I tried switching to it yesterday from Opus 4.8 ("/model" command) it didn't complain, but I didn't actually send anything to it when I saw the cost was like 2x Opus 4.8. ie switched back

I'll try to remember to actually try it tomorrow and see what happens.