Ofc the author is arguing for such a policy because an actual min wage increase won't pass congress.
Regardless, a minimum wage isn't the floor wage. There are workers on tips who can earn lower than min wage workers. There are undocumented and even documented migrants who earn less than citizens, many times less than min wage. Even among citizens there is disparity, though they are typically paid atleast the min wage.
To have an actual floor wage which no private employer can break, you'll need a universal job guarantee which will have the Gov set the wage and employ anyone at the said wage. This forces the private sector to pay everyone including undocumented migrants the said wage.