I read it as a complete rejection of Obamacare and Federal intervention in what should be the State's business. The voters of Missouri obviously don't want Obamacare in their State and aren't willing to spend State money on it. Perhaps the message is, "If the Feds want this, let them set it up and pay for it."
If Missouri had set up an exchange, the Federal government would have funded the cost of doing so. This initiative prohibits Missouri from accepting the money.
The Federal government will partner with a Missouri non-profit to set up the exchange. Missouri residents will be required to purchase a qualifying health care plan if they don't get one through their employer. Taxes will be imposed and subsidies granted just as in any other state. The end result will be improved health care for the people of Missouri.