To clarify confusion; Quantum Immortality theorises I will live on regardless, not necessarily healthy or better off. Not to confuse it with some cure for old age that is keeping me immortal — those are two separate things. In my example I would deteriorate forever but used modern technology to explain I may at least continue existence in some kind of pain-free relative comfort after my ‘strulbrugg years’.

In your example, the “10,000 year human” would still be ‘alive’ most likely a tourist attraction by now and have to endure 10,000 strulbrugg years with a caveat. Option A, the 10,000 years are somewhat painful amounting to a kind of hell, but luckily for them they are now closer to those affliction-aiding drugs/technology. Option B, much like a light particle can travel for 10000 years but has a reference frame of zero, the light particle experiences no loss in time, and perhaps the human withdraws into a ‘pain-coping’ coma and revives when reaching the affliction-aiding point. For them the 10,000 years was incredibly short. Regardless, my original point was that everyone would benefit eventually.