Given the nature of your gallery, the fact you mention it is a "male skull" (an oddly specific thing to note) and "PROUD TO BE A LESBIAN" graphics, this piece has (in context) hostility towards male heterosexuality.
The addition of the rose, a symbol of traditional heterosexual intent, could be interpreted in many ways.
My first thought was that you sought to insult/violate heteromale identity by adding a delicate flower - but that is something they chose to do in life, to sacrifice their lives, their bodies for society, for their wives, for love.
So as a Men's Human Rights Activist, I choose to interpret it this way: Don't die a fool for love, traditionalism or feminism, all of which demand the disposability of men for their own ends.
Or it's just the interpretation of there being beauty in death, as the title suggests.
I fear you're delving too deep into a pretty picture. With photography, often times the artist looks at something, thinks 'hey, that would look cool!' and sets up a shoot around it/ That's happened with me quite a few times.
However, sometimes there is a deeper meaning, but I don't think 'oppressing' the heteromale identity was it.
Also, I am not the original artist. Only they can tell you the meaning behind the photo, but I'm fairly certain you're getting hurt for no reason other than your own sensitivity.
It's actually not so easy to get an actual human skull into your photography studio, so there's likely not been a choice on who the model would be. Could you whiny Men's Rights activists stop for once interpreting a piece of art as an assault on your tender souls when you see a something that might probably-perhap-if-you-interpret-it-in-the-right-way connected with your social / political opinion? This only sours the art for others who simply want to view it, and makes artists think twice about certain topics they might use in their art.
Same for the Female Rights Activists who behave the same way. Just start to think and save your energy for the real problems out there. No offense meant towards all activists who don't mewl about nothing. Don't make art political unless it intends to be.
Live free. And let others live free, think free, and choose freely what kind of art they make.
Yeah. It's odd, but apparently in the comments section, some friends announced two years ago that he/she had died. The official notice shows the gender as male. So I don't know. It's weird because the account is completely contradictory, but he/she hasn't been on it since the supposed death.