Generally speaking, doing something that is more favorable toward the other party of a contract (i.e. paying out extra dividends to bondholders) and less favorable to yourself (i.e. Obsi keeps less money) is totally fine and would not be considered a breach of contract.
Generally speaking, a contract has terms that state that the favored party's failure to enforce a provision does not amount to a waiver of tha provision. Also, generally speaking, contracts are enforced using lawyers and judges (unless there is a binding arbitration clause, in which case they are enforced that way). The GLBSE, and presumably this contract, fall outside of "generally speaking." With nefario being the judge, jury, and executioner when it comes to GLBSE, it is not unreasonable to avoid breaching a contract in either direction. Moreover, Obsi has stated the funds will be placed in a buffer, which implies that he is not keeping more or less money as per your example.