"The 21,600 pound (9,797 kg) GBU-43 bomb, which has 11 tons of explosives" says the release.

Well 11 tons is 22,000 lbs and 11 tonnes is 11,000 kg, and  there is guidance system and casing to consider as well, so they are suggesting an obvious physical impossibility regarding the explosive composition of it.  

Hopefully their intel and aim was better than their math.