This decision must have been part of the "Amazing Thailand" ad campaign. Look, the Thai government is looking for HiSo long stay retirees, who they figure can afford the cost.
The starting cost for these plans assume you've never had any issues -- not as much as a sneeze. Someone with hypertension or cardiac history, or heaven forbid cancer in remission need not apply.
I was wondering about some of the hesitation wrt lack of participation was not just safety but applying for a less effective vaccine in which the recipient sacrifices international travel to many destinations that don't recognize Sinovac.