What do you mean by orphaned?

I suspect the problem you are running in to is with athletes who authorize your app and then stop using it without revoking access. From your point of view those tokens are no longer in use but since the athlete still has your app connected in their account, Strava considers them as a user. With the app still connected to their account that athlete could potentially come back and begin using your app again without having to authorize it, so unfortunately there isn't much you can do. There's no API call which allows you to remove an athlete from your app so you're stuck with either requesting a limit increase or hoping they some day revoke authorization.

That is also my understanding - current when a user disconnects we we try to process a revoke against Strava, but that was not always the case, and if there is an issue with that revoke we drop it rather than hold stuff up.

I was interested to know if Strava had a mechanism (or any plans to implement one) to allow an app to clean up these orphaned tokens