Nice try, but Citadel is the largest market maker and if it were an exchange (ostensibly, it might as well be one!) then it would be almost as large as the CBOE!
You can just look up the relative sizes of those firms, you know. It's funny that you came up with CBOE as your reference, because you can look up how big CBOE is, too.
He’s trying to say that cboe is a particularly funny reference as they process minuscule equity trades. Which makes sense given they are an options exchange…