Your post kind of contradict itself. For once you say they aren't harashers but they are opportunists. Like plating a demo charge on an abandonned forward building. But isn't that harassing?
I use the term harassment infantry to signify a type of unit with abilities allowing them to circumvent and disrupt defensive positions and/or battle lines.
Eg. Spawning units in a building behind enemy lines, using smoke to cover a flank, some kind of fire up ability, stunning, fire, are all examples of harassment behavior.
The airborne can drop behind enemy lines but they'll lack the firepower to do much without an upgrade. The airdrop has its uses but I find it secondary.
The airborne are sluggers and opportunists rather. Their abilities give them DPS and staying power and they can more thoroughly take advantage of a weakness.
Eg. You cause a base rout on the enemy and an OKW medic truck is left mostly unguarded. You can drop and equip an AT gun while your Airborne plant a charge and achieve in seconds what would have taken well over a minute for an AAHT.
Eg2. You're facing a KT but manage to fire a rifle nade and land an engine crit. A P47 can now diwndle it to a sliver of health on its first pass. Whereas it would otherwise casually back up to safety.
And how can they be more adaptable than rifleman while having less abilities? They can't really keep a strong battlefield presence either with those overpriced weapons drops.
They have a suppression ability, nades without research, high DPS when upgraded, can reinforce on the field next to a radio tower and self heal with vet.
The commander as a whole is more adaptable because of airdropped weapons.
You did bring up scouting like i did. This is why i suggested some changes to the pathfinders to actually make them better at this job. That 4 man squad really is a pain to hide.
The most important use of pathfinders is to provide LOS for your troops and battlefield awareness so you can properly shift your forces.