Rebookings raise all sorts of issues that don't apply to what you earn when you book a flight with multiple segments.

In general, credit is awarded when you get on the plane and get off somewhere else. Doesn't matter whether you were booked for that flight ten weeks previous or ten minutes previous, whether you got the ticket for $$ or when you weren't on another flight (for whatever reason).

So, when the flight you're rebooked on is longer than the one you were originally booked on, you get credit for what you fly. The same thing happens in reverse: if you had been rebooked on a shorter one, you would have gotten fewer miles. In that case you can often get "original routing credit" if the rebooking was the airline's fault (e.g., mechanical). If it was for missing the flight, as it was in this case, asking for ORC could be considered greedy - though some people would, and sometimes they might actually get it.