Honestly, it sounds as if they Devs are trying to say that SF do *not* have special abilities, though perhaps they simply emulate another unit type (infantry, MI, or cavalry).
If that's not the case, then shame on them for asking for proof that requires lots of effort and special circumstances to collect just to prove a point. Actually, that works both ways. I know that you might be bound not to reveal bits of how the game works, but it's just being jerks when you compensate by demanding the impossible of people, as if it was no big deal. Most of these suggestions are impossible to disprove, and pretty near impossible to prove if they are true, because of how little we know on how they work.
Further, I believe the wiki actually says that they have special abilities. Or did, at some point, if it doesn't still. Somewhere.
Older SF centers--those in Makar, specifically, have proven special abilities. To use Makar as an example, some of the men have a charge ability--I guess you could call that cavalry, sure. But the others will act like they have siege towers--no other unit in the game does that.
What is unknown is if there are newer SF centers that have abilities.
