Make the man disappear

The man is a first class asshole, that's for sure.

While you loath taking the life of someone unnecessarily, no matter how much of a scumbag the man was, your creative mind quickly came up with another method.

A kage bunshin and a henge found the man's attention being diverted away from his food, where a drop of sleeping potion knocked him out for the count. No one really cares about what is happening, especially your henged bunshin is buying a round on the house using the man's money.

You then quickly transport the unconscious man onto the next boat scheduled to travel to the Land of Snow, putting him in one of the rescue boat. Just to make sure he wouldn't appear soon, you made sure to empty his wallet of money and ID, the latter you tossed into the sea.

It was a despicable and honorless action, but hey, you're a shinobi, not a samurai. Besides, the man was clearly aiming to cause trouble to Tsunami, forcing you to take preemptive action.