Park Sinyim; Taro's best friend for oh so many years. Taro claimed that the creature was that person. However, he had no way of proving it before the fight or after. He had put it all on belief, hoping that it would work out the way he wants to.
But for that to happen, the creature had to reveal himself. And that didn't happen. Taro hoped for Park to reveal almost instantly and hug it out or something. Therefore, he never expected the hesitation from his best friend's part.
While the hesitation continued, Taro was confused by his own right. "Now wait a minute. If he is indeed Park, how come he knows Malayalam. I mean, I haven't turned my translator into Wadorian yet, then how?" He questioned in his mind.
It didn't take him much to get to the bottom of it though. If Park was taken in by the MIB, then he would've got a decent translator. But by the looks of it, it didn't seem like that would've been the case.