It said a lot about how attentive Gustave could be that he'd figured something out. This hadn't been a permanent or long-lasting thing, it'd only started after a certain point, so... "I... want you to try this first. I think the problem might be in her formula."
When he'd asked, they'd said the organic stuff was the best choice, so he'd gone for that. Along with what Azelma'd actually asked for, of course. "It won't be an immediate fix, but... you never know?"