This is not how waivers work.
Hernandez will go through waivers (unless he is traded before), and if he clears, the Tigers can outright him. A player outrighted does not re-sign.
Now, Hernandez is a bit unique, in that he does have enough service time to declare free agency, but that would require him forfeiting the rest of his guaranteed contract, which is well beyond what he would get if he hit the open market. In short, I think you meant to say he will accept the outright assignment, which is true.