Nah, Sorte is a tsundere, but Aina has been making it very clear from the start that she wanted to be his slave, talking up how she wanted to be summoned for night services but then chickening out When Wendy let her sit in the cuck chair. He's the one that didn't want to treat them as slaves, and he's only distanced himself further after they dropped down to criminal slaves, he's even half-assing the sexual harassment.
I'm sorry, but making the Elixir with Moongrass proves nothing but the fact that, it too, gets consumed, not that it is required. Attempting to make the Elixir without the Moongrass and failing, now that would have proved it requires Moongrass.