"They were challenging my sexuality," he told 9Now. "My sexuality is my sexuality. I'm straight. I don't have to justify it."
Speculation online about Billy’s sexuality mounted when his nude modelling past was revealed.
However, the reality star explains he decided to take part in the shoot to raise money for a male suicide prevention charity.
"Why would I even need to set the record straight? My sexuality is my sexuality," he told Daily Telegraph.
"I'm as straight as an arrow but for somebody to actually say their sexuality just shows how immature some of the Australian population is about sexuality.
It’s my bloody business. I’m completely comfortable with my masculinity and these people that say that I’m gay, it’s simply because they’re threatened of me."