I think it would depend on the individual. Some would admit it, once they see the whole globe through that glass it would be like trying to say apples don’t exist in response to someone handing you an apple. Their senses would override the belief. They might not wanna admit it…

Then there would be the people that are fanatics about it… They would probably get hysterical, or check out mentally, or get violent, or some other sort of emotional break. I would also guess these people would be unwilling to go into space in the first place.