Could hyperbaric oxygen therapy make us age slower?

No: I presume the answer is no as there is no scientific study related to this issue. In fact high oxygen flow for too long can cause inflammation in the lungs and that's studied. For normal people, there is enough oxygen in the air.

I don't think that : There is evidence for halting the aging process at this time. But, i wouldn't be surprised if if was advertised for this purpose. Approved uses for hyperbaric oxygen include: decompression sickness, gas embolism (arterial), recalcitrant soft tissue infections ; osteomyelitis, gangrene, carbon monoxide poisoning, wounds or skin grafts/flaps that aren't healing w standard tx, crush injuries, thermal.

Hyperbaric medicine: There is no evidence for that this condition is helped nor hindered by hyperbaric treatments. I am afraid that aging is subject to the humor of the tincture of time.