I just interpret it differently. Brand is not used to having power or having ANYONE listen to him. He noted how alluring it was to just order the Aves around and not worry about their feelings on the matter. But instead of musing how he'd love to keep doing it, he uses it to explain why the Quetz (not queltz; quetz, as in Quetzalcoatl) are such a bunch of psychos.
Its not a red flag so much as him trying to do a good deed the most expedient way possible and explain what's been going on. It wasn't malign, what he did. Just grossly under thought, half-baked and to the exact wrong audience. Saida should have told him sooner just who these Aves WERE. Now they are in deep poop, because Saida revealing herself will just get them handed over to Vetra FASTER.
They're still slAves. But the one they are bound to obey without question, their commander in chief, ain't erzatz Saida.