Larry Craig was arrested under a questionable law that makes it a crime to use offensive words. Using a secret sting operation to enforce that law is most likely unconstitutional. Secret sting operations like the one set up by the police in Minneapolis are not designed to stop anything. They are designed to arrest as many people as possible - sometimes arresting people who had no intention of doing anything illegal.
Of course government has a legitimate interest in keeping public restrooms free from public sex. But it has no legitimate reason to use undercover officers to encourage sexual activity to ratchet up its arrest statistics. A warning sign and patrolling by an occasional uniform officer has long proven to be the most effective means of stopping the inappropriate behavior. In fact, that's exactly what the Department of Justice and the police departments of major cities including the Minneapolis Police Department recommend. Police should spend their time at airports on more dangerous threats.
Sen. Craig has not been a great supporter of civil liberties in Congress. But you don't have to endorse the civil liberties of others to keep your own.