If this is the case, then we have escaped all reality for the sake of making easier solutions. When an unexpected service change happens (the key word being "unexpected"), there isn't time to just magically cancel all of the trains that we don't want to reroute.
Look, the for example runs 25 trains. Those trains have to be sent somewhere. We can't just say, "Oh, lets ignore those 25 trains because the is suspended." If we're do that, then we've entered fantasy land.
And no, I don't agree that most of the scenarios would be "f**ked* if we counted these trains. I think my solutions usually do count those trains, and they work perfectly well.