This is just me, but you could look at the conversation between Clark and Henderson like a dance. Each are approaching each other and backing away with their words. Weaving around the same idea: Clark is Superman. I don't know if that could help or not, but as a writer, that scenario could help me have fun writing the dialogue between the two. I agree with the others that it would be really risky of Clark to come outright and admit his dual identity, so have some salsa dancing mixed in that charges the atmosphere.
Henderson is baiting Clark with his theories, which I like. And I like his charge of emotion when Clark tries to swerve around his outright claim of him being superman. I think metaphors would be fun for you to have Henderson use. Before he gets angry enough at Clark's avoidance of his main theory, and is therefore reduced to having to say it in plain words, he could suggest to Clark that "The apple doesn't fall far from the tree, if you get my drift." Or "Seems there are two peas in the same pod." Or something like that.
I hope these suggestions take no offense. It is only meant for the intention to make your story stronger. I like the plotline that you have going! I'm curious to see how Clark is going to figure out a way to "break out of jail," as it were
