I would think that the technology for cryo freezing people would have been newish by 1999, so there probably aren’t too many people from before then who woke up in 3000. There may have been a few people who froze and unfroze around the same time, so he may not be THE oldest, but I think that he’s the oldest person in the series
There were Neanderthals in the episode “Fun on a Bun” but I don’t recall if their bodies were frozen for eons or if they just lived as an isolated society for ages. Nevertheless, boneitis 80’s guy would still be older than Fry.
I also think that age should also be measured relative to the character’s perspective (or at least the perspective of their body). In essence, cryo freeze for 1000 years = 1000 years of aging, but accelerating 1000 years of time in a matter of 5 minutes from the traveller’s perspective = 5 minutes of age.