I find it an uneducated generalization, why 11 nations of different cultures are lumped together? But, I can see nothing denigrating.
Sout East Asia is a division of Asia just like Middle East (Iran, Afghanistan, etc) and East Asia (Korea, China). Countries in the South East even has a union known as the ASEAN (Association of South East Asian Nations) so I don't think it's an uneducated generalization. It's more of a geographical clustering.