@Mere****
you are having smoke blown up your back side. :O
There is NO rule now (nor is one coming out in the new year) about a person attending university (or even a private school) needing to be on an ED visa. :/
There are people who work here on Non-B visa/extensions and attend university, there are people Non-O visas based on being married to thais, other foreigners or because they're raising kids here who attend uni.
ALL of them do it on the visa extension they have without the need to get an ED visa.
You do what you want, BUT definitely know you're being sold a pig in a poke. I have no idea why they're pressuring you to get an ED visa but know you definitely don't need it to go to uni here.