Beverly mentioned that line, as if it wasn't exactly unusual, and Archer (or maybe Trip?) made a remark about it as if it was the norm....I don't think Vulcans live quite that long. Sarek was barely over 200 when he died.
Depends on if the Morilogium is delayed by having DNA from another species present. Linnis and Andrew both seemed to mature fast (as Ocampa do), but they might have lasted more than nine years. Or, maybe Talaxian DNA is more dominant than human... it's possible that Neelix and Kes's children would have Talaxian lifespans.
Maybe the caretaker did something to the Ocampans along with regressing their psychic powers as well. The caretaker def babied the Ocampa from realizing their true abilities and potential.