Well if the contract stipulates the royalties as being the market rate then they have a case. If the contract stipulates an actual value of the royalty I don't see them getting very far.
“The fundamental cause of the trouble is that in the modern world the stupid are cocksure while the intelligent are full of doubt.” - Bertrand Russell
"When the power of love overcomes the love of power, the world will know peace."
Jimi Hendrix