Ah! He sounds just like me.
I had odd parents... said one thing, meant another. Put on the show of being 'friends', stern but fair, concerned, loving. Always knowing best!
If I was a good girl and always told the truth, told them where I was, who I was with, all would be well. So I did and got told no.. over and over again. For the slightest of reasons... DM didn't like the sound of it, didn't know that place, those people. I had to prove myself... how I am not sure, as I was always told I wasn't mature enough, was a follower, would be led astray. I never lied, always asked, always accepted their decisions.
I went along with it until I was 16, in VI form and travelled independently each day. I was still controlled, DF would randomly drive by college to check I was there. I was enjoying it and wouldn't have dreamt of skipping classes. But that didn't stop the constant surveillance, questioning, accusations.
Then I chose to just stay out.. no mobiles then, so I rang home, told them what I was doing, who I was with, general area I was in, when I would be back. Then put the phone down. They called the police - who told them I was 16 and as I had phoned, I wasn't missing! DF drove round aimlessly looking for me. Getting angrier and angrier.
I left college. Well, DF found me a bedsit and moved me in, as I was old enough to make my own decisions now! Yet still they spyed on me!
So I moved 200 miles away and didn't contact them for about 3 years.
DSIS just lied to them. From about 13 she went out on all nighters hundreds of miles from home, pregnant aged 15... all the things they were sure I was doing and never had! They never quetioned her... she was more mature, more trustworthy!
Sometimes being right about your kids is stifiling, you don't see them growing up, you keep that idealised version in your head for far too long.
I doubt OPs DS thinks of himself as immature, just babied. He isn't a follower, just never has opportunitites to be himself, to find out.
I bet he'll be terrified to come home and will arrive late and belligerent. Then, when he has weathered all you choose to throw at thim, he will decide that all the hassle is worth it... and you will lose him, maybe for a short while, maybe for years or forever! That will be up to you, your next move!