If the aircraft has no true accelerate-go capability, the FAA check airman should not be requiring candidates to compute it.
However, if it is accepted that at some point, even an Apache could fly at least with some small climb gradient on one engine, I suppose that point in the flight path could be said to be the accelerate go distance. Probably impossible at gross weight, but just achievable at some lesser weight.
Upon reaching 50 feet and assuming the gear is up and prop feathered, blue line speed reached - maybe that's what the examiner was really after to see if the candidate had a grip on the reality of flying a low performance twin?
At a guess with only two on board, that would probably have the accelerate-go somewhere around 3000 metres, so do-able from a major airport, but clearly not from your average county airstrip.
Of course, if one really did have the luxury of a 3000 metre runway, accelerate-get airborne and land/stop would probably be a better distance to have in mind! That one is not in Piper's books either. The marketing people of the day would not have wanted it.