That might have been a logical conclusion to jump to when it was suggested there was metahuman involvement and he was the one under arrest, but most people, Sitwell suspected, would have preferred denial at this stage, assuming it was the other party that was using enhancements and insisting there was no way they were a mutant, or trying to skirt their guilt. After all, 16 was late for abilities to first manifest. Mr. Kaplan must have had some inkling before now. Clearly, he just got his confirmation.
Once more, Sitwell didn't answer, letting Mr. Kaplan ruminate on that for a beat under the agent's patient watch, waiting for Mr. Kaplan to search through his own memories for his answer, before continuing his interrogation. "Let's start at the beginning. What is your relationship with Mr. Kessler?"