Do you think there is a chance to make the two compatible somehow (that would be a dream for all current and potential GSX users of their great sceneries)?
I think the issue is similar to what happened with LHBP from LHSimulations, but they contacted us and we solved it easily, adding specific code to GSX to protect their scenery objects.
I tried downloading the Demo version of both sceneries, but it doesn't seem to include the custom jetways, so I couldn't test it properly (strange way of calling it a "full featured demo"...), so I had to guess what the problem might be looking at a message on their forum.
Have a look at the attached file, it's supposed to protect any object in the Simobjects folder with a title starting with "DrzewieckiDesign" from being removed by GSX, I hope that works for both sceneries, let me know if it's working with the full version.
Put the attached file in the following folder:
FSX\fsdreamteam\Couatl\GSX