It's possible to detect when someone else uses NotifyInspect during your waiting period and re-fire your event. Still a nuisance, though.
If Blizzard doesn't provide a better way to handle things, I may have to go write a LibQueueInspect that does this properly, once, so we don't have a bunch of separate implementations that step on each others' toes. Maybe I could get Ace or somebody to include it.
It would have to handle stuff not being returned, probably with a fairly short timeout, and re-send requests as necessary. I'd also have to add some sort of priority system so that an inspect-happy addon got pushed back in line if an addon that only requests a few now and again asks for an inspect.
Anyway, I'll give them some time first. Hopefully they'll get it right.