Mike,
Since you both belong to the same club, I'm assuming( dangerous!) that you two are well aquainted. My initial approach would be a one on one conversation with him in private. Maintain your temper, but be firm about how you feel. Explain to him that his ethics regarding your area/stand are unacceptable and you are appalled by his actions towards another fellow club member.
Maybe a bit of guilt will cure his indiscretion.