I went on Easter and asked the guard checking my bags about monopods. I did not have one on me but I had been looking to purchase one (which I did a few days ago). I asked if monopods were allowed, she asked if it extends, I said yes, and she replied that if it extends it is not allowed. That was news to me, so I asked about tripods. She said if extends then no. I asked, so no one can bring in tripods or monopods for video taping? Got the same answer.
I think it might be case by case but there is a big difference between selfie sticks and a tripod or monopod. I don't think she really knew what she was talking about because I asked other guards on the way out and they said yes, they were allowed. If they give you a hard time, have the site ready on your phone if you need to pull it up saying it's allowed and don't be afraid to ask to speak to their manager about it.