You're missing the point, tossbag.
Your expertise is in assessing whether a person meets the competence standards or not. You can and should be doing that, whether or not the person presents with CASA's thought bubble form. As you say, if you thought he had problems you would have assessed it that way. As soon as you are part of a process through which a medical issue is identified as being the cause of the problems, you are at risk of finding yourself in the middle of a time consuming and stressful controversy. But it is your choice.
Just in case I wasn't clear, the assessment form I filled out for this chap had no medical questions on it, it was assessment of competency standards regarding tasks to be undertaken on a flight. The fellow held a CPL at the time and was since diagnosed with a spectrum condition. I saw it as CASA guarding their arse, I'm tipping they can't just say "Bloggs has just been diagnosed with a disorder but it should be ok." Perhaps I was foolish in taking part in an exercise like this but at the time I was comfortable with what was being asked on that assessment form and that it didn't ask me to do any sort of medical judgement.
I guess I'm in a severe minority here and that the majority of instructors would say to this fellow, "yeah/nah" ?