if I were you, I'd call the airline for verification. If you can get a straight flight through BKK, it'll undoubtedly save you a lot of money and stress.
I don't know what day you are traveling but I chose Feb 15th and searched on the Sky Scanner app. The first screen shot shows some flights where you must self transfer but there is also a flight where you do not have to self transfer (see the 2nd screen shot for flight details) and the 3rd screen shot shows several flights where you do not have to self transfer.
That will be very difficult for your friend. However, if he/she has a couple million Baht in the bank, well established & verifiable employment, and ties to the local community (e.g. owns a home, children in school, etc.) then it is probably possible but it is a very complicated process.
Lemme see if I have this right. You trust them to get you a visa that cost you 600K THB (or more) but you don't trust their instructions with regard to the process of picking up the visa?