It is NOT utter bullshit. It is completely possible if you think about it with an open mind. The astronomers cannot disprove this theory either as all they do is just observing the reflections. You can observe as much as you want, you cannot prove it's not a hologram just by observing it. The dome is indeed quite big, but not infinite and not like it is believed now ~14 billion light years.

Here is where the conspiracy starts, as according to this hypothesis all the space probes to the Moon, planets etc are fake. They cannot be real as the celestial bodies are just reflections and not located where we're observing them.