Ah, I understand what you mean.

Well I'd say (and some articles back me up) that if these symptoms (goal orientated activity, hyper-focus, agitation) have been constant since symptoms of AS first appeared, it may not be mania you are seeing.
Like I said, the depressive episodes may be more clear-cut. (though a bipolar diagnosis needs only a manic episode to be present AND is not better explained by another disorder- one of them being a disorder with prominent irritability)

If the shift in behavior was sudden and not present at time of AS symptoms, then it may be a manic episode you described.

That being said, it is possible for someone with AS to be bipolar. It is probably just diagnosed later when it is easier to really nitpick (or split hairs) as to which symptom accounts for which disorder.

In my opinion, I feel that the hyper-focus on whatever grabs his attention at the time (exercise, sushi restaurant etc.) sounds more like symptoms associated with AS. I may be wrong. In my case, the drive to complete a certain activity is usually met with confidence and almost a 'superpower' feeling; in other words, as though I can do anything.
When I become agitated, restless and have that energy, I feel more the urge to release the energy by whatever means neccessary
That is where it'd be tricky- one could say he had that drive for a specific task is because of drive, or you could say it is because that repeated activity was releasing (or soothing) that energy in some way (even to his own detriment). One could even argue a bit of both.

So even if I really stick to my own opinion without saying "I am on the fence because a professional would be able to differentiate", I am still on the fence because the symptoms overlap so much that he would perhaps be diagnosed with BP later on. Professionals sometimes see lack of need to analyze everything in great detail to separate something so close in nature.