The idea is that people with little wealth or income will be able to put small amounts of money aside in a government bond that can be used towards your eventual retirement. Obama seems to be of the mistaken belief that to open a 401K requires a large down payment and this solves a problem that doesn't exist. Also, poor people don't want to give up a ten or twenty every week because they NEED it now. Taxes is also a problem since ALL tax law comes out of Congress. Congress has not taken this up and so any promises made by Obama are just that? Promises!
Since this idea has all the substance of a mirage (executive order) the money put aside can just be collected by another executive order in the future. So your money goes to the government for that bond and government can just decide that you don't need it anymore. Bye bye money!