Many thanks and sorry, i'll write oliver, he told me it would be up to you!
Alright, I've checked again, and found an email from Oliver of 2+ years ago, which discussed some additional work he did on his own on ENBR for FS9 to support AES, because how the scenery is made, and this was done by tweaking the FS9 .BGL files.
The issue is, he can't do it in FSX anymore, since the objects are in FSX native format, and they can't be excluded in the same way, since in FSX we are not using .BGL files to store terminals anymore, but use C++ and Simconnect to draw objects so, that method wouldn't work anymore, and it would require considerable support on our part, both on the scenery and more so on the Addon Manager itself, that would have to work together with AES.
Considering that more than 2 years have passed since that email, I've just forgot this specific issue with ENBR, but Oliver never requested anything related to having ENBR in FSX either, that might have helped recalling what the problem was...
ENBR is the only airport we did that was made in a way that would require *that* specific additional tweaking, later sceneries were made from the start taking into account AES, so I can't say we have too much of an incentive (considering all the other things we are working on), to modify both the scenery and the Addon Manager, just to have ONE, 3+ years old Cloud9 product, working in the FSX version of AES.
So, for the time being, I'd say you should consider ENBR to be non AES-able in FSX.
