I think the logic is that if your retired you can't work for a company. There is no mention of investment and every retired person with a pension has an investment.
Depends on where you stay, if in Bangkok or the like it would be possible, however, your miss out on a lot of local shops, restaurants and street food.
I did not ask, as I was getting uk bank charges and I decided to close my account. They have a online form, if you search for gov.uk "International pension centre" you can ask them, they respond in one or two days, back by email or call them.