This time, Watson sent Hans to find out whether the treasure map was true or not. He didn't expect Hans to do that.
Parker was supposed to do this, and it had nothing to do with Hans.
The reason why he used Hans this time was that Watson felt a little uneasy. He was trying to use Hans to deceive others.
Recently, Watson felt that something was wrong. His actions were always monitored outside. It was a bad feeling to be watched all the time, which meant that he had been seen by others. He didn't know who the person was, but he felt uncomfortable with the enemy in the dark.
Watson always liked to take the initiative. The feeling of being monitored made him restless.
If he couldn't find the person behind them, all his actions would be exposed in the eyes of the other party, which was a devastating blow to their treasure-hunting patterns. No armed force liked to be monitored.