Wow, the things she's listed as 'concerning'! He just sounds like a four-year-old!

I think the research you've done is great and the pre-school should consider the same and have a think about the expectations they're putting on the children. The way he reacted when you told him you were disappointed I think tells a lot about him, he's a sweet boy and he knew it was wrong; and in his mind there was also a 'reason' - I wonder if the teachers actually spoke to the kids about it?

I think your response is perfect and you sound like a wonderful mum with a wonderful boy