The girls,however, would also say the man, and that would be heterosexual rape.
There is no rationale in law to decide that one is more traumatic than the other.
Of course there is, crimes that do more harm to the victim are treated more harshly. If you agree that young boys raped by men would exhibit more trauma, physically or mentally, than young boys raped by women, then that is the all the proof you need to sentence the homosexual rapist to longer time.
If it is true that young girls suffer equal harm from homosexual and heterosexual rape, then you would treat that differently.
In either case, it isn't Anthony Kennedy's decision to make.
I agree that young men raped by men would suffer more trauma than young men raped by women.
However, I don't agree that they suffer more trauma than women raped by men.
Rape is the crime, whether heterosexual or homosexual. There should be no distinction in sentencing based on supposed trauma, as that is a subjective judgment.