Nit-picking. None of you are wrong. But that doesn't contradict citizen's argument. On the contrary, it reinforces it.
I could say, in the same line of though - and be completely correct - that I am at the center of the observable universe. Not earth or any of you.
Citizen was instead contradicting the homocentrism expressed in the bible and by most religions, by observing that the center of any observable space is always relative to the point of observation and is fixed in time.
This may not be the case at all if you live near - and are under the effect of - certain phenomena that heavily distorts space-time fabric like black or white holes. Your perception of the observable universe may differ depending on which direction you are looking.We are able to see equally far in every direction