not disagreeing, but i think a part of why ML wanted MC to be an Omega was mainly the part about bonding/ mating bc Omegas can't leave their Omegas afterwards, since they suffer/struggle with their heats afterwards, since being with another Alpha is no option anymore due to their body reacting with rejection towards them (usually it's also the same with anybody else so whatever).
obviously it's different in every omegaverse, so idk and i don't remember if it was mentioned in this one.
I guess the main point is that ML does not want MC to ever leave him. i am quite positive that ML loved MC for a very long time and just wanted the extra insurance that MC would never be able to leave him.
I can already guess, the reason why the ml is obsessed with turning the mc into an omega(and being so happy that it worked), is cuz of something he went through. Some backstory sht, about how ppl around him was obsessed with the traditional alpha x Omega pairing. This sucks, it feels so icky knowing the ml couldn't just love the mc for who he is... Instead, he changed the mc to fit his "standards/type". Now I'm just gonna patiently wait for the groveling arc lol please make him kneel, beg and suffer so bad mc!