Sorry to be gross, but hear me out on this one.
Imagine for a moment if, hypothetically, a man who was anally raped by another man could become "pregnant" with some sort of a living being the size of, say, a grapefruit, that would grow in size for 9 months inside of his scrotum and then be forcibly ejected through his urethra and out of his penis.
Something tells me that we wouldnt even be debating the "abortion issue" if this were the case.
If men could become pregnant, abortions would be available at Jiffy Lube for $79.95 and could be performed at the same time we got our oil changed.