Thats not entirely true. When Mass closed and I re-opened it a year later, we did not reset anyone goblin stamp totals.
Other chapters that had similar closing/ownerchanging/reopening situations have wiped everything.
Though typically, yes. If the chapter closes, your GS are gone. Otherwise i have not heard of any chapter saying that after X amount of time your goblin stamps are no longer valid.
So yeah. basically what they said.