by Richard Oelmann.
No, restrict access settings work at a different level to assignment dates, so whatever the assignment dates are (extension or not) if it falls outside the dates permitted by and Restrict Access settings then students will not be able to get at that activity.
I haven't looked in detail at the advanced restrict access settings - I believe though that they can be made complex with AND/OR kind of provisions - so can you make the access available (restricted) by date OR user name/group (make a group with one member?)
Again - don't know about this, haven't tried it and just brainstorming possibilities as I am in the middle of reinstalling my dev environment at home (wet bank holiday activity ) so don't have access to test right now.