That's not a separate kind of guy, is the same marshaller, but it's being placed on a ladder, because the program has calculated that, based on your eyepoint and the stop position, you wouldn't be able to see him, so a ladder is used, just as in real life.
Of course, the Stop position, as calculated by GSX, might not be very accurate, not because GSX makes wrong calculations, but because the only data it can use, lacking an airport customization, is the scenery AFCAD, and the only thing the AFCAD provides, is the center of the parking, which is far too limited information to allow GSX to calculate a realistic Stop Position that would work with different airplane types.
Of course, you can customize all of this, both the Stop Position ( which, when customized, can be separated from the AFCAD parking center ) AND the Marshaller position, so you can place them both in a way that it won't force the Marshaller to be placed on a ladder if it's not required.
I suggest reading the "Understanding the Stop Positions" chapter in the GSX manual.
