It is exactly what you are saying: that the federal government has the power to enforce the Bill of Rights against the states because it is not prohibted from doing so.
Does not follow. You contend that I argue that anything not prohibited is allowed. What I truly argue is that which is prohibited, is prohibited; what is allowed is allowed. Some things to the Feds, some to the States, some to both. Then, under the 10th A., undelegated powers not prohibited are reserved to the States or, ultimately, the people.
Violation of the Constitution is prohibited to both, via their officer's sworn oath. The BoR are part of the Constitution, therefore violation of same is prohibited to the States.
I have not argued power to enforce either way, your assumption that I have notwithstanding.
Morally one can certainly argue that the BOR should have been followed by all the states- one of the reasons for the BOR was to protect those rights we had reserved from our state governments.
But the Founders did not give the federal government any such authority.
At the time pople trusted their states, the state governments had led them in the war for independence, they refered to their states as their "country" in iterature of the time.
The new federal government was greeted with almost as much suspicion as the United Nations would be today! Much demand was made to restrict it's powers to matters between the states and to foreign affairs.