Encourage him to be open and honest with his psych... it sounds like he does want help so he might be receptive to your explaining that if he just "puts on a good face" for the doctor it's not going to help him pin down and deal with his problems.

It does sound like aspergers is definitely worth considering. Some of the other symptoms (anger, depression, etc.) could be secondary problems which have arisen because of his difficulties in growing up with aspergers, but not actually part of ASD itself. People with aspergers can have a really hard time in life and secondary problems like anxiety, depression, anger, etc. can develop as a result of the difficulties that arise from life with ASD. I'm not saying he definitely has aspergers, but pointing out how the things that don't fit exactly with ASD can still fit the situation.

Not all psychiatrists have a lot of experience with ASD, so hopefully his does have some... if he agrees that it's a good possibility then maybe he can refer you to a psychiatrist who specializes more in ASD. Anyways good luck. I think based on what you've posted it is 100% worth seriously looking into.

Also, looking back at how he was as a child can be helpful in diagnosing ASD in adults. If you're going to present your idea of him having ASD to the doctor it might be good to read up on ASD in childhood and use his childhood behavioral history as evidence (if he displayed a lot of classic ASD behaviors when he was young it will really further your argument). Interviews with parents, siblings, etc. about a persons childhood history is often used in diagnosing ASD.

Also, looking back at his childhood and comparing to what you've learned about ASD might point you in a different direction if you don't think it fits so either way it can be helpful. Good luck!!!