''Gay'' is just a word
Fragment of a discussion from Comments:Australian teacher drops 'gay' from kookaburra folk song
Not all people who use gay as a negative have that attitude. Use of wikt:gay adjective #6 is not incompatible with respect for homosexuals, championing of their rights or being a member of the GLBT community.
That usage of the word is derived—if my memory serves me correctly—from the common derision for homosexuals. Besides, I am sure homosexuals will be offended by the use of the word "gay" to mean "bad", in the same way a woman would be offended if "female" were used to refer to something as despicable.
I believe you are correct as in to the derivation. I have never heard a gay use the term, but I have heard a couple of bisexuals use it on that meaning.
Better example over "sternum": w:phagocytosis and all related terms.