The regulator of one country which now builds mainly twins (777, 787) wanting to make it difficult for the quads (340 series and 380) built by another group of countries. If you make quads obay the same rules as twins after an engine failure then some of the economic advantages of them disappears.
I don’t think that it IS the case that "quads" are made to obey the same rules as twins after an engine failure. For instance, 121.565 speaks to continuing after engine failure, and says (in part):
Sec. 121.565 Engine inoperative: Landing; reporting.
(a) Except as provided in paragraph (b) of this section, whenever an engine of an airplane fails or whenever the rotation of an engine is stopped to prevent possible damage, the pilot in command shall land the airplane at the nearest suitable airport, in point of time, at which a safe landing can be made.
(b) If not more than one engine of an airplane that has three or more engines fails or its rotation is stopped, the pilot in command may proceed to an airport that he selects if, after considering the following, he decides that proceeding to that airport is as safe as landing at the nearest suitable airport:
(1) The nature of the malfunction and the possible mechanical difficulties that may occur if flight is continued.
(2) The altitude, weight, and usable fuel at the time of engine stoppage.
(3) The weather conditions en route and at possible landing points.
(4) The air traffic congestion.
(5) The kind of terrain.
(6) His familiarity with the airport to be used.
The language of 121.565 is nearly identical to the US Civil Aeronautics Regulations, Part 40, dated
31 December 1955. How this could have been written in 1955 to disadvantage Airbus in 2005 is beyond me…
Although I haven’t seen anything from the FAA on this, my guess is that it isn’t going to be a battle fought under the “nearest suitable airport” banner… Of course, I am prepared to be corrected.