I was gonna vote for or at least imperial and saying that I liked how “driving” the inactive route was mandatory to get the 2 Cash.
But why limit to CASH Routes? This is too powerful in my opinion, because there are almost always Inactive CASH Routes, which are worth ~2 Cash, so this is basically a 4-Cash Route.

But the same Route with “If they have any Inactive Routes” instead would be interesting.

It’s intended as a ~4-Cash Route that you can’t effectively use in bulk.  However, I’d also like to point out that it’s also (for the purpose of making money) like a Highway Route that gives 1 extra Cash.

Well, a Highway Route actually gives more than one extra Cash, since it lets you decide which Route you want to make Active (as long as you can afford enough dailies to process through Inactive Routes)
As for bulking, I’m not sure what you mean. I think someone who has enough Cash to Scout for an Extended Route would have no problem combining them with Airport Routes.

I was reading the proposed route, saw the rule, and thought “wow that’s going to be worth a lot of Cash”; as Bucky says, it’s like a more powerful and harder to control Highway Route. (It must be limited in a way that excludes Highway Routes and itself, incidentally, or there’s a combo that could end up potentially overpowered.) Then I saw the scouting cost of 13, and thought “yup, the author realises”. Powerful if you get it, but has a cost commensurate with that. (I’d rather buy 2-3 Highway Routes, I think. How did they end up so cheap?)