Consider this:
You have three fruits; A large apple, a medium-sized orange, and a small apple.
Saying "The apple is the largest fruit" is meaningless.
Even saying "The large apple is the largest fruit" is tautologically redundant.
I completely see where you're getting at.
But if you would have made the statement not so technical and just appreciated its good humour I'm sure you would have enjoyed it as much as I did when I read it. Instead of trying to prove it wrong by saying not all floors are the same therefore how can you say that it is bigger than a shelf.
Sometimes it's not a good idea to pick apart things until they become unfunny.
Ayo, doesn't it seem like you're just being attacked for the fact the floors make great shelves?
I dunno' 'bout the rest of these weirdos, but the floor literally holds everything in my house; it's an amazing shelf. 
It even holds *more shelves*!!
Talk about efficiency!!! 
Word up.
I don't need a closet or any of that shit.
I have my bed, desk and mother fuckin floor.
Chairs work too...