I hate being fair to these people, but Cheatle needed to be at the convention to observe her SS team in action, show that she was in command, and make darned sure SS agents weren’t in the cloak room with hookers and “DEI Digest” or otherwise failing. Plus, Mayorkas probably ordered her to show the flag to forestall the inevitable criticism if she didn’t.
Cheatle literally running away from questions might not have been the image he hoped for...
In addition Trump asked her to come there to talk to him. I’m sure she could not refuse that invitation and, because of his schedule, I’m sure Trump had to schedule the meeting there.