of everything you posted, this makes the least amount of sense.
how does it matter how he died? what if he died from a heart attack while in Iraq? or what if he died freeing 5 captive americans and leading a blazing gun battle out of an Iraqi prison, one wounded soldier slung over his shoulder, and killed 15 insurgents before taking several rounds to the chest? if that happened, would we get to know not only if he was gay, but if he were more top or bottom?
the point cannot be altered. this was a gay man. people knew he was gay. he worked vigorously to end the DADT policy. and he died in the service of his country. if an obituary is going to get into his life and personality, then this detail about his life, something that he obviously thought was pretty important, should be mentioned. and it's omission is what is homophobic.