Seren, it can be really difficult for them to perform without the understanding of the entire staff. Keep in mind, he may not even be diagnosed.
From the small amount of education I have had on this, you had to adjust to them in that you really could not have a high level of expectation that they are able to adjust their issues very well according to environment even.
It's also worth mentioning that since it is a spectrum, he will be more or less successful depending on how far along they are on that spectrum.
Does your work have an EAP program? If so I would suggest contacting them for assistance! I just used ours for the first time today and I cannot believe all the things it can assist you with!
Good luck friend!