He is either not broadly educated in the subject or is either consciously or subconsciously limiting discussion through a nationalist perspective, probably both. The guy's from Vietnam, which was previously substantially Indian/Hindu[0], significantly Muslim[1], and essentially much Vietnamese culture came from China, which was also the dominant script[2] until the French era, and he doesn't discuss any of those cultures. Chinese traditions of naming are the structure of Vietnamese (and Japanese, and Korean) names. Then he claims to discuss SEA, which is a huge area and in historic terms largely a metastory of India[3] vs China influences with a lot of Arabic impact thrown in, and none of these cultures are mentioned.

[0] https://en.wikipedia.org/wiki/M%E1%BB%B9_S%C6%A1n [1] https://en.wikipedia.org/wiki/Champa [2] https://en.wikipedia.org/wiki/Ch%E1%BB%AF_N%C3%B4m [3] https://en.wikipedia.org/wiki/Abugida#Indic_(Brahmic)