I doubt the MSMA has the athority to call for extra testing without consent. Here is basically all that has been said, from MottoGPMatters.com
However, the rules also make one exception: Rule 1.15.11 allows for "any activity authorized by Race Direction." With the capacity changing for 2012, a gentlemen's agreement almost certainly exists between the factories to allow the factory riders to test the 1000cc bikes outside of the regular schedule.
According to that, Paul Butler has the athority to OK a gentelmens agreement, but mot the MSMA itself.
Not quite. The MSMA tells Paul Butler that they have agreed to extra testing for the new bikes. Paul Butler then allows the extra testing to go ahead, without imposing penalties for extra testing. The existence of the gentlemen's agreement is kept among the factories, and not discussed in public, as there is no need to do so.