I will argue that the Disco bit is more intended to add some subtext that outlines Admiral Vance’s thoughts than just “haha we eat poop.”

I read it as tiredness on Vance’s part-- a sort of signal that yes, in some ways the quality of life under the Emerald Chain is better than the sterile closed environment of the UFP’s remnant. Contrast this with Osyraa’s statement about how she has real apples. He chooses the Federation’s integrity when it comes down to it, but he was genuinely considering throwing the Federation’s legitimacy behind the Chain.