I voted mature rating...
But I also think the mature rating is more of a "legal" stopgap... It doesn't have any true age verification technology attached so ANYBODY can blow right through it.
So if the image is in line with the tone and theme of the series, it's not gonna be much of an issue either way. It's not gonna be a shock value deal breaker.
Nicely done image by the way.
PS: Isn't it kinda weird we don't have to follow the same mature rating warnings/ect. INSIDE the forums?!?