In vanilla xcom interceptor pilots are abstracted and thus fighter type aircraft do not have any crew. In modded games your soldiers often double as pilots and any craft capable of mounting weapons will have at least one soldier aboard. This creates a problem, if there are crew aboard a craft that shoots down another craft, the game will assume it to be a dropship and immediately ask you if you want to attack the crashed target regardless of the player's intentions. This is annoying and slows down the gameplay a lot, particularly in the lategame when you often sortie multiple craft at once.
So the idea here is to add an option that skips the ground assault popup if your craft only has pilots aboard. There is a very easy way to detect this, all you need to do is check the craft inventory for equipment, if there is nothing at all then clearly the player does not want to use this craft for ground assaults under any circumstances.