It does happen with the KNF as well. They are quite openly supported by NLH.
Still, I think the statement needs to be clarified. The BPA does not "ally" with those groups. We merely tolerate them in Bretonia. Our diplomacy states any Kusarian factions as hostile and we do treat them this way.
Blood Dragons and Golden Chrysanthemums shouldn't be in Bretonia, in my opinion. The two Blood Dragons I encountered up to now were asked to leave immediately. One complied, the other not. The latter one found his ship destructed afterwards.
So, the BPA you saw today most likely escorted that GC - escorted him/her out. Anyways, we will see what it was about as soon as the responsible constables have made their patrol reports.
Note: all of the above is only about Dragons and Chrysanthemums.