HR at every large-ish organisation I have ever worked for has been really clear that you can still be liable to the organisation for your behaviour away from official functions and this has undone colleagues of mine at unofficial after work piss ups. This is part of every anti-bullying, discrimination and harassment training I have ever done.I'm not sure if he was wearing the company tie when he 'got intimate' with this lady. But even if he was I don't believe he was representing his employer at any stage in the proceedings. Same as the GWS boys were not representing their club when doing silly stuff at a private party.
Your boss wouldn’t be identifiable as part of Company X at the strippers, and it sounds like nobody had any issue with his behaviour (and rightly so).
The GWS boys were clearly still representing the club as they were easily identified as a GWS group - sanctioned, or not.