By the way, I did get your inquiry into the face emoji and OP meanings. As far I can tell, the emoji signifies if that poster is online or not - grey and indifferent is offline, smiling is online; and OP means original poster.
I agree with DNJ that in this case it means original poster. However it sometimes used in the body of a post to mean Other Person and if you look at some of my very first posts it was also directed at me since my name was Old Pilot.
