I had to look-up who James Gunn is. One thing I observed is that James Gunn is today a 51 year-old who a decade ago was 41 years-old.
His remarks were they made at 14 or maybe even at 24 years old, would be thought merely a joke in poor taste and something borne of youthful imprudence. At 41 and in 2009, however, there is a legitimate expectation that an adult would have more empathy, prudence, and maturity than to joke about rape, which is not a joking matter. There is nothing funny about others' misfortune, most especially not one's having been violently abused, raped.
Some people perhaps ascribe to moral relativism. I do not. What is and is not within the realm of good character, what is morally/ethically right and wrong, has been the same for thousands of years. What changes over time is culture's approbation and forbearance of what's wrong, not what is wrong. 2009 is not, however, that different from 2018. It's safe to say that a 41 year-old in 2009 should have known better than to abstractly, blithely make merry about the occasion of rape.
And, no, there is no moral equivalence among all ribald remarks. While all of them are in poor taste, some are beyond the pale. By the time one's 41, one should know better than to say things that one would not care to later in life have others evaluate them against whatever then be the cultural mores. Frankly, if one
is indeed a good Christian living a life of Christ, good Muslim living as Muhammed/Allah instructed, good Hindu, Buddhist, Sikh, Taoist, or even Zoroastrian, the notion of eschewing such insouciance toward others should be one in which one is well practiced.