Being the devils advocate
Heres a strange possibility maybe the DM due to the fact English is not his mother language confused buddy and friend so when he said Girl Friend meant Girl Buddy in lieu of Dive Buddy, trying to be politically correct in his mind. He was being overly attentive as he was worried due to her aforementioned conversation prior to the dive, shame we can't hear his side of the story.
Tips are based on interaction / performance with the clients, due to this I would certainly not complain and jeopardize his job, as there could be a perception issue here.
I do not think it strange; in fact it was my first impression... along the lines of cultural differences.
What if our molester should show up with the following post?
Hello, please excuse if make mistake, my English no so good. I was employment as Dive Master helping visitor enjoy the splendor of my waters in Mexico. Captain ask me pay special notice this lady visitor she is afraid. We made jokes and I try be special helpful make comfortable. It was not challenge this lady very nice. Now lady say I hurt her and not employment now. Has this happen to anyone Dive Master? What did you do?
For those of us from litigous societies we forget that SOMETIMES just mentioning a problem is enough to fix it in the rest of the world.
And too, the false accusation cast's a negative shadow.
I can hear it now..."I heard that DM so and so molested an older female diver,
several times, several ways. She was a very strong professional woman well versed in harassment yet could not get away from him."
"Good heavens! What happened?"
"All I know is he held her down underwater and he must have threatened her somehow because she was afraid to make any complaint until she returned to the US."
"Well, that does it for me. Reginold! I do not care what other people say about it there. We are not going to Mexico!"