i'm not sure it's so black and white, AT&T advertised that
iPads ordered or purchased before a certain cutoff date
were eligible for the unlimited plan. i believe it was around
July 10 give or take so if he can prove his was ordered
before that date they might just give it to him.
as for it being no longer available, well i sold my 3GS and
had a Nexus 1 for 3 months before going back to the iPhone
and all it took was a little begging to the right supervisor
and i got my unlimited plan back. so anything it possible !