What objection would they have had to the National government regulating trade

The major objection to the National government regulating trade was complete ceding of trade powers held by the states to a more powerful government, especially in the absence of a bill of rights for the protection of the interests of the small states.

Explanation:

These days, politicians have come to the understanding that state-level services, procurement, and investment policies should be left to the state's legislative houses. Some agencies have also been created to ensure the harmonious relationships between states and the federal government on trade issues, especially international trades.