The argument goes like this:
A business employs some people at $10 an hour (which is the minimum wage in this scenario) and other workers at $12 an hour. These are the two lowest pay levels at said business.
Now, the minimum wage gets raised from $10/hour to $12/hour; what happens to the employees who were paid $12/hour before the minimum wage is increased? Their wages won't be increased (or so the argument goes) any time soon, and wage increases for them will actually be delayed, yet they have seniority and experience over the minimum wage employees.
Is this a valid argument?
No.