On the other hand, I'm a glutton for punishment. So I'll give it a try.
What was Satan bound from doing?
Satan was bound from deceiving the nations in to going in to this final battle.
Remember, bound just means restrained.
Remember Job?
Satan was bound from taking his life, even though he was totally active in other ways.
Satan really wants to gather the world for this final battle with God.
Well Satan was/is bound from doing that.
Ok, Christianity definitely spread big time for 1000 years. So during that time Satan was bound.
How could we explain the major push back against Christianity the last 1000+ years?
Maybe, he was released around 1070ad, and has been working toward that final battle?
It's a potential interpretation for those seeking a literal 1000 years.