Judy, I, too, am appalled that this happened. And I would certainly never want to attend this event unless what happened is resolved... and quickly. And I am sure Susanne will take steps to do so.
I am also certain Susanne will not think that you are being a bother at all. Any producer would welcome a level-headed report/discussion about an incident like this 100%. After all, the next time the "security" person acts out in this manner, it could be much more serious.
And, it's not a matter of "punishment". An employee of the club assaulted a patron. The patrons must be protected, therefore he MUST be removed.