@George ******
DTV is certainly not the only visa you can get when you are over 49, because non-o retirement starts at 50.
DTV is not an education visa, so your remark "Learning is learning" is totally meaningless here, DTV is for soft power and remote work, scuba diving also has nothing to do with soft power,
The fact that some embassies did approve thai language as soft power does not mean it really is a valid soft power item.