I think sentenal and kazmaka aren't on the same page.
First off, I think sentenal is saying that Crono can't be dead, because he's going with the Crono=Miguel thing.
Second, aside from that, kazmaka might be slightly confused. Could Crono live more than 1,000 years all the way to 2,300 A.D.? No, but that's not really how the Dead Sea works. You see, Chronopolis was kind of sent back in time during the Time Crash. Dead Sea is the area that Chronopolis is, in a timeline where Lavos wasn't defeated, the ruined future. So that area was essnetially sent back in time. (Some people, including myself, believe that you're essentially stepping into the future).
So, Crono living 1,300 years isn't relevant, as all you would have to do is step into the area. Keep in mind, Miguel is also from the 1,000 A.D. era, and he wouldn'y have lived that long either.