Just my thoughts, but Thai doormen in bars is a fairly new thing, a few years ago the girls would handle situations like this, I used to marvel at how patient they were with drunks, helping them out and putting them on a motorbike to get home.
I know times have changed, but would he have slapped a Thai girl? I doubt it.
Have always myself been against Thai guys working inside gogo's, even as waiters, in farang orientated nightlife, just causes jealousy, as they will form attachment to girls working there.
There is a new chain of bars in Pratumnak and Jomtien that employs Thai doorman, Why? For the once every 6 months a farang play up