You could always take a photo of your head nearby afterwards under similar lighting and photoshop your unmasked head over the top.
As the previous post stated, given the state of play with the pandemic and the relative age of the actors, it makes sense to be wearing a mask.
You wouldnt want to live with the guilt of potentially, unwittingly giving COVID to a Trek legend.
I would just pursue a refund if you aren't happy and hope the stars return to a convention when COVID is endemic and more under control.
I am curious for the purpose of this thread? Was it in hopes to get people to pick up pitchforks and side with you and rage in anger?
We can't get angry at the event organizers or the celebrities, they are just looking out for their safety. As MrWax stated above, these celebrities are going to be meeting and posing with hundreds of people, that is 100+ chances they could be coming in contact with the virus.
This is a result to the new spike in Covid cases. If the trend persists, we will see these shows canceled altogether again.
I am almost 100% positive the event will refund you with no fuss as they know that people might not want to do this and I am sure they are more willing to refund those individuals.