I use Aerosoft My Traffic 2010. This problem doesn't exist for other FSDream products like Hawaii, LSGG.
The scenery use proper airline codes, just like all the other airports.
The only difference might be that all our gates are flagged as GA, in order to remove the default ground vehicles but, this shouldn't be a problem, if your AI have their airline codes, which is normal for an AI product, because the airline code will take precedence over the parking type.
The only possible reason is that, if My Traffic reads the .BGL file for some reason, perhaps to generate traffic, it might have been confused by the parking type and might have skipped to generate traffic there, but if this is the case, it's a problem of MyTraffic, since the sim itself is certainly capable to assign AIs relying only to their airline codes, regardless how the parking type is flagged.