The Marines were not chosen for this "domestic law enforcement" mission by accident. The Posse Comitatus Act of 1878 specifically applies only to the United States Army and, as amended in 1956, the United States Air Force. Passed as an amendment to an Army appropriation bill following the end of Reconstruction it limits the Federal government from using Federal troops to enforce domestic policies within the United States.
The Navy Department, and by extension, the Marines are under no similar restrictions, although, at present Navy policy is to adhere to its provisions.