A dodge. Either he didn't know or he didn't want him to know. And regardless of which it was, that statement issued instead was not something he could respond to directly. Whatever you do, don't self-incriminate.

Well, if Batman was allowed to reply with an evasion, he should be too.

"Your Japanese is very good." Because that was a common thing to say to any foreigner who spoke even half-passably. And it was true.