Anyways, I'm sure you can understand why a political event, where many of them do rely on RFID access badges for certain personnel to enter certain areas, would not want someone with a device that can clone badges.
If you go to a political event like that... just take your actual key. Not a device that spoofs your actual key. What you're proposing is essentially saying you have a legitimate reason for carrying around a lockpicking set, because you use it to enter your apartment when you forget your keys. It's pretty understandable there are high-security places that won't let you in.
I've carried a flipper zero with me to use as a copy of my key when I misplaced my original.