So??? Mexico is a soverign nation and it's Courts are empowered by it's laws to apply it's own provisions to bail bonds. It's no different here or in Europe, the Far East, or any other soverign nation.
When you are in another country you are subject to that nation's laws. Bellyaching about it doesn't change reality. Chapman is accused of violating Mexican laws and failing to honor the requirements of his bail bond that he agreed to. Even the Court in Santa Barbara California found that he acted without authority in this matter and rejected his claim for any reward or "bounty" moneys.
I and others might agree with you if it was just a case of "rule of law" but Mexican Gov't officials and police are corrupt. When they are concerned about the "rule of law" of other nations then Americans will respect theirs.