It isn't so much as the use of the Rabbit Head Logo (the official trademark name), it's the inference that "if XYZ fraternity is using the Rabbit Head Logo, then Playboy must be sponsoring the fraternity party", which in reality it isn't.
In the olden days when I was an undergrad and dinosaurs once roamed the earth (don't worry, it's only the 80s
), it was not unusual to see blatant rip-offs of commercially-trademarked logos used to promote fraternity parties.
I remember one fraternity using the logo of Vuarnet sunglasses as the theme for their Victory Party (at OU, the big weekend party every fraternity has on the first home game of the season), simply replacing 'Vuarnet' with 'Victory'. Beer distributors didn't even think twice printing up plastic cups with fraternity letters (except for Fiji, which prohibits the use of their Greek letters upon anything not considered permanent in nature.) Back in those days the stuff was printed in very small numbers and was seldom seen outside the university community. This was well before the NCAA suddenly got religion and started administering licensing for the the schools.