I guess one of the main problems would be to fill out the rest of the army with troops who have a high enough moral standard for the KTS to even consider working with them. Only people in the sphere who would probably be humanistic enough for that are, well Haqqislam, and that would pretty much make the KTS NA2 look like Starco does for Nomads; technically a Faction Sectorial with an abundance of troops... or just like (a copy of) QK. if they, on the other hand, manage to expand on the KTS with more Kaplan troops (light kaplan infiltrators? Kaplan HI?) sure, why not. I mean, Druze have only 4 other troops (AHB, Bashi, Brawlers and Hunzakut) and they work fine as an army, so Kaplan really wouldn´t need that many new units.
I imagine they'd get Brawlers since those are just standard mercenary LI seemingly. Beyond that its hard to guess - dunno how Haqq they'd lean - some, sure, definately borrowing the Haqq remotes and possibly a unit or two. Who else might they draw on?
I'm guessing CB scoped out several potential NA2 armies and determined that it was too difficult to make a Kaplan-centric list that was different in play-style/aesthetics to StarCo. With four NA2 armies already, adding a unique and interesting fifth one may not have been possible. I suppose the follow up question is: Why not put KTS in StarCo? I feel like the answer would be: Because then nobody would play any other units. Let's just assume that QK is your ticket to running a KTS-themed Sectorial. You've got Kaplans (of course), Hafza can pretend to be your Brawlers (Similar costing, BS 12 with Arm 2 and Rifle+LSG, as well as being Link-team glue, except ironically for Kaplans), throw in some Al Hawwa (present in StarCo, so legit Merc choices) and maybe some SHI like Azra'il or a budget TAG and call it a Merc company.
I don´t know about them getting brawlers, they sound more like scum and villains. Not really something Kaplans would employ. On the other side, they might be so broad in term of who works as a brawler that might not be a problem. I guess there are as many good people with high integrity as there are lowlife gangsters. Well maybe oneday QK will become a NA2 in their own uprising, now that would be something I would like to see (if for nothing else than the forums xD )
I guess you could do some cool stuff with Remotes in a KTS Sectorial. Borrowing a Bulleteers, Rudras, Tsyklons or maybe even a SuJian. I love to play that! For other Merc troops Nomads are certainly possible, but it's a bit redundant with QK and StarCo. Maybe JSA troops would fit too? They seem to have their honorary codes and some already work for Merc companies. Having Ryuken would be amazing and Kempatei used to be Mercs anyways.
Kaplan Tactical by themselves aren't really a "rival" of anyone...but yeah, KTS don't like Druze. At all.
Well, with the Foreign Company your dreams of a KTS merc group have been realized. Rejoice and enjoy. ;)