I removed the SODE XML file from ProgramData\12bpilot\XML. Now there are large red Xs where the jetways used to be.
First, I edited your post, because you posted images that weren't accessible.
Are you sure you removed the SODE XML files ? If you see red X, it means you removed the SODE Simobjects, and left the XML in place because, the red X is an indication from SODE that a SODE XML file is calling an objects, but it couldn't be found in the sim for any reason, which can be either the object itself missing, or the scenery not configured correctly, as if it was disabled.
Nothing to do with GSX, the red X are the indication of something that is happening entirely within the scenery own install and its SODE configuration. GSX doesn't use the SODE XML file, and it's not affected by it, and if you have an issue with GSX jetways, you won't see the Red X, because they are appear only if SODE itself is creating ( more precisely, failed to create ) jetways or other objects, but GSX jetways are created by GSX and animated by SODE so, no red X if you have any kind of problem related to GSX.