>> This is the militia model envisioned by the Founders Police forces are a relatively recent invention
Yep. And there is absolutely zero constitutional justification for federal police forces or police powers.
Actually to a degree there is. The Constitution says the President has "shall take Care that the Laws be faithfully executed"(Article II section 3) which implies the ability to enforce, and George Washington himself led the military to enforce collection of alcohol excise taxes during the Whiskey Rebellion.
But a strict reading of the Constitution would strike down most federal laws as unconstitutional.