Saturday's (Feb 17) post drew widespread attention and the Queensland Nationals MP was accused of being insensitive in the wake of last week's high school shooting in the United States.
Federal Greens leader Richard Di Natale referred the post to federal police.
But Mr Christensen says there is nothing wrong with putting a joke up on social media.
حمّل تطبيق أس بي أس الجديد للإستماع لبرامجكم المفضلة باللغة العربية.