Here is my take:
You can validate that the fly in the room prevented him to fall asleep (he felt annoyed).
You can validate that he was ("must have been" badly served at the kebab's
You can validate that he felt ("must have felt" disrespected and got angry
You can validate that he had ("must have had" an awful night in the police cell
You acknowledge his experience of things so that he feels heard, understood.
You should not validate the invalid (i.e: the aggression - throwing a mayo bottle at someone). If he went to the pub, I'm assuming he got drunk (?). That's not a healthy coping mechanism. So again, something NOT to validate.
The rest are the consequences - spent the night in a police cell because of hitting someone with a mayo bottle. Pure facts, it's the law. You're not "on their side", it's just what happened. Hopefully he'll learn the lesson.
But observe the difference between these 2 when he comes back in the morning:
1 - "Hey you! where have you been, you've been drinking again I bet? What happened!"
2 - "Honey I'm so glad to see you! I was worried something happened to you - are you ok? Tell me about it"
There is a great video on validation by Alan Fruzzeti that you should watch, he goes deep into the subject:
https://bpdfamily.com/message_board/index.php?topic=206132.0