He's a sysadmin. He has access to every single screen name on the boards here (everyone here does via the 'search for users' function). He can get into any account at any time, just like I can access any account on my family forum because I'm sysadmin for that forum.
The owners own this forum--nothing on it is yours or mine. They can do whatever they want, whenever they want. I'm not sure what you're complaining about since you knew this when you agreed to the TOS.