I wish I had been able to find a preschool for my kids which was JUST about the social aspect and play-based, but also with an emphaisis on learning classroom skills like sitting down and listening (at least at around age 3.5-4...younger kids don't necessarily need to be able to do that), organizing their stuff like coats, backpacks, etc. They did do those things to some degree, as well as learn how to interact with other kids, and that was the main point of sending them. But there was way too much time wasted on boring academics like the alphabet, numbers, etc. For kids who already know this it just teaches them to hate school at a young age. My DS in particular started to act up and as soon as they got out the academic "stations" he would literally make a run for it. Unfortunately all of the preschools around here focus on academics like literacy...and it's way too easy. So my kids spent 3 years learning the alphabet. I didn't push for anyone to give advanced stuff at that age--I knew I would just end up looking like a pushy tiger parent because what kid needs to know how to add or subtract large numbers or read second grade level books at age 3-4? I knew that's what they would tell me. So we worked on those things at home, as far as my kids were interested (and DD was more interested than DS at that age). We suffered through the boring academics but it wasn't ideal. In terms of dealing with the immaturities of other kids...this is going to be an ongoing saga throughout the educational career, and at some point kids need to learn how to deal with it. Not necessarily at 27 months, but they should have some exposure and develop the skills to deal with it before heading off to kindergarten.
It sounds like it might be a good idea for you to look for some informal opportunities to socialize and put actual "school" on the back burner for now. Or else look for a school where he can interact with older kids and there is no emphasis on literacy/numbers. I don't think you will find one that will teach him at his level (although I could be wrong...who knows). A lot of kids don't do any preschool until they are 4, here, and they are fine in kindergarten.
