Miami has never made sense as a destination for Hayward to me. If he's looking for more money, then Utah is the obvious choice over a Miami. If he's looking for the best path to the Finals, winning, and a sustained bright future, then Boston is clearly the better choice over Miami.
Literally the only advantage Miami has over the other two is the night life scene/weather, but I think Hayward is one of the few NBA players where he's not really into all that stuff.
I think this is mainly Riley putting this crap out there to increase his chances. After this Finals series, I think he's more likely to leave than to stay in Utah, and I think we're the only realistic destination for him to go to meet all of his goals.