I have been thinking of this and after some thorough analysis I came to a conclusion that this is NOT bug using or cheating, but rather using two inherent features of AS.
1) connecting traffic rights from non-traffic rights point if the passenger airline has traffic rights on the first leg
2) EU treaty traffic rights within the EU.
Based on the above, it is not bug using per my opinion.
Why?
I give an example:
A US-based airline, with USA traffic rights, establishes a hub in London, for example, from where he flies to other destinations. He will have traffic rights USA-via Europe-to final destination. This has been long known in AS and accepted, though it was not easy to pull off financially, because you needed a lot of flights on long haul planes (expensive)
Now let's take this a bit further.
A USA airline establishes a subsidiary in Venezuela. This subsidiary will have USA traffic rights, meaning it cannot take passengers in Venezuela but can take inbound passengers from USA. This airline can run a route from Caracas to any major USA city, and to any major Latin American city, and it will have traffic rights between USA and those Latin American cities, via Venezuela. If he has sufficient flights, he can live off connecting traffic, IN CARACAS WITHOUT TRAFFIC RIGHTS IN VENEZUELA AND WITHOUT ANY TRAFFIC ORIGINATING IN CARACAS.
The capitalized point is the one to keep in mind when we now move to the Quimby case of the STN based airline.
This airline is connecting EU-originating traffic (to which it has rights - e.g. CPH-STN) to a foreign point (e.g. ORD, ATL) through a point from which it does not have any rights (STN). It also does not have right for any passengers originating in STN. Same as in the previous example, the Venezuelan subsidiary of USA airline was connecting USA traffic (to which it had rights - e.g. MIA-CCS) to a foreign point (e.g. GRU) through a point from which it does not have any traffic rights (CCS), and as well it would not have any traffic rights for passengers originating in CCS.
While I understand that running CPH-STN-ORD and having connecting rights on the route may seem as bug using for a France-based/France-rights airline, it actually is NOT. It is the same as USA airline using Venezuela for connections. The only way, in my opinion, to prevent this, would for the E.U. treaty (and corresponding within-EU traffic rights) be abandoned in AS (which, of course, will not happen, and neither it should happen!).