Is the gate agent actually boarding all those passengers when Mosaic is called or are they just gate lice? If they are being boarded, I'm sorry to say but that's something I would report via social media or Contact Us page. The GA's job is to enforce the boarding rules so that the process is consistent across stations. Part of being Mosaic is having that privilege to board early and get acclimated to your personal space.

It also bugs me when non-revving crew pre-board ahead of Disabled or Mosaic passengers. I've seen it happen in multiple cities. I feel like Disabled and Mosaics should always be first to board and then any exceptions can happen before Group A.