Imagine if somebody you worked with came up to you one day and told you that the way you perceive the world is different to everybody around you, and that your behaviour is upsetting to other people you speak with on a daily basis, and that the only way you may ever be able to pass as 'normal' would be to visit a therapist and spend years in therapy... Do you think you'd appreciate that?

I think nowheretohide is correct, it's not really your place. Learning you have an ASD can be a very traumatic thing to go through and your suspicions because he behaves differently to how you would expect, is not a medical diagnosis and could cause more harm in the long run than good.

I know from experience that people telling me similar things in my life before I was diagnosed just made me feel isolated and very upset because I didn't know why I was being perceived this way or why I struggled so much to fit in with other people and be accepted by them. All it ever did was make me pull away from socialisation, which really doesn't seem fair.

In the line of employment, it's the job of your boss to make sure he doesn't cause disruptions to the other employees at work. So really, he's more to blame for allowing any such behaviour to continue, than the person who may not even know he's being disruptive in the first place.