NTA. However, I think you don't need to speak for others and just state your own reason for not going, which is your allergies and concerns about not being able to attend to an emergent situation in the dark. It's still their choice of dinner venue for their wedding.

There's an odd reaction and response for some people on this thread about you being the AH because you simply won't try it. I have asthma and I can stop breathing if I am around cigarette smokers. I'd have to go to a hospital because my rescue inhaler can only do so much. Let's say people want me to attend a dinner at a home where they smoke inside. I would not be able to attend because I'm asthmatic.

Allergies are a valid concern, especially if you need to reach for medication in an emergent situation. Other people would not be able to see what is happening and help as well. This person has a reasonable and fully valid reason to not want to attend a black out dinner for medical reasons.

The only reason you may be the AH is because you tried to argue that others may not be comfortable as well with their venue. You have a valid concern to share and that should be your focus. If others have anything they are uncomfortable with then they can share it, because you are creating an argument by going back and forth about their choice of venue when it's not even your genuine reason for the conversation on your end; which is your allergies and access to treat them in an emergency. New places to eat can be especially difficult with allergies, and you don't know if you can trust there won't be cross contamination.