Would you be upset if a man you're seeing "exclusively" refuses to let you post pictures of you together on your social media? He said it would be "premature."

Guy I've been seeing for 3 months refuses to let me post any pictures of us on social media. I'm just trying to show him off and make it a point that we are together. However, as in previous posts, I have referenced that he says I am not his girlfriend, yet we are in a relationship. It makes no sense. But I would like your opinions on why he does not want me to post him on social media? We are not friends on social media so it would only be people I know that see it. He said this is premature. Advice?