I am sure Kaiji did not intentionally try to trick Kazuya, but to be fair, considering all of Kaiji's big brain deductions, one might reasonably expect him to realize what Kazuya's personality is like and realize honesty in this situation would be misinterpreted.
That said, to be fair to Kaiji, he can be such a straight-forward person sometimes, he might not have known how to be strategic in that sort of way (as opposed to a circuitous strategy in a game).