You don't pay income tax in the UAE, so it's likely a good reason why he is there now, whilst he continues to draw his healthy annual payout from West Ham.
His 6.5 year contract extension signed with West Ham in 2017, has only just expired in June this year. When Reid departed by mutual consent in 2021, it was reported West Ham still owed Reid, £6.5 million. But they reached an agreement that would see the club paying a figure in the region of £5.5 million, as installments. Presumably over a longer time span than the then just 2 years remaining on his contract.
So maybe there is just no financial incentive, to play for any club outside the UAE. He'll keep himself fit - maybe he does Steven Taylor bootcamps - and then if he ever finds the right UAE club/feels the urge he'll put the boots on again.
Or maybe by say 2025 the West Ham payments stop, and he moves back to London, as is no longer any financial reason to stay in Dubai. At age 35-36 could he play for Leyton Orient, Gillingham or similar. You couldn't rule it out completely.