Yes, foolish. He ILLEGALLY went where he was told NOT to go, he landed on the beach, and tried to give them “presents” They tried to kill him. He swam back to the boat, and then the next day...He went back. He committed suicide by Native.
God wants His word spread, but He also said don’t be stupid.
God said don't be stupid? Book, chapter, verse please. The closest word you will find is "foolish" and the consistent context is unbelief.
If God called him to reach this people, it is neither suicide or stupid. It's obedience.