Is it normal he is treated this way?

Yep. Their house, their rules. Have you considered the rules they made have contributed to the person you love today?

He is still living under their house. Their house, their kid, their rules. I mean, some people aren't so strict with their kids after 18, but they may believe it's best for him. I don't know if he has a job or a car, or anything that shows responsibility, but they may also not see him as an adult yet(for one reason or another). They may feel like they are preventing you guys from having sex, and possibly becoming parents. It's all about the point of view.

He must prove his rules are more likely to create a better environment and regulate social life better than theirs.
Then it's all downhill from there.... It is the best way to prove you finally became responsible and are able of taking your own decisions. Like: dad? It is better If I do what you want me to do in about two hours or so, because... (understandable reason here) Or like: mom, I have to do this because if I don't... (plausible consequence here) Leave yourselves post its and notes everywhere remembering you when to do what they want, anticipating them. So they do not get the whole thrill out of ordering about. And then you can go: I do all these things I deserve some more freedoms! (like you did them out of your own choice, because you wanted to)
So he can go like: I have been doing everything that was expected of me! I think I earned a chance to do (whatever they don't want you to do) he just has to learn how to bent the reward/punishment/forbid routine to his own needs. Once the parents notice he does what is expected of him without them having to order him about, they are likely to loosen up the collar and keep the leash less firmly in their hands.. That's when he can start bending some rules.. It's not about "standing up to them".
Duh.

From past experience I'd stay out of it!!

Let him do what he wants or they want. If he's good to his parents he will be good to you :o) Anyway, you don't want his parents to hate you for trying to change him - his life will be miserable at home.

Keep your opinions to yourself and enjoy the time you two have together.

Don't waste it by nagging at him!!

You haven't known him that long there's no telling way he's being treated like that and he can grow balls when he moves out his parents' house

My parents loosened up on me once I turned 18, but I think it's perfectly acceptable for parents to still enforce rules while someone lives under their roof.

It's hard to just break a habit/attitude when you've been living with it for so long. You have to understand his parents probably have a foundation built in him of years of treating him this way, a girlfriend who saunters ino a situation and try's to change the family's ways may have some issues with digging him out.

Have u ever seen school of rock
Ok this chick is her partner not o join dewy I think his name was
anyway she's telling him to grow some balls and stand up for yourself and then he leaves the chick because she was being a bitch to him