I checked the community rules, just to be sure, and there is no rule against male posts. But every time a man posts an image, it is immediately downvoted.
I understand that some people might not be interested in seeing that, (I'm more of a boobs guy myself) but there are gender tags on every post. It shouldn't be a surprise when you click on a post with an [M] in the title and see a cock n balls.
Feel free to avoid the penises if you aren't interested, but why discourage the guys who are willing to share with people who are interested in seeing that?