This and the IT trade make it so clear why Hayward did not show any loyalty to the Jazz. It is a two way street and if teams across the league don't give it to players they can't expect it in return.
OK
Players don't owe teams "loyalty"
But fans of teams, by nature expect "loyalty" and there can be no passion, no devotion by fans to the teams they love if fans don't have irrational expectations and desires.
But "loyalty" aside, Hayward handled the situation poorly. That's all on him and there is really no question that he flopped in that regard. He also should have refused to consult with the Jazz on their other roster moves if he wasn't heavily leaning towards coming back. That was BS, but the FO has more blame on that than Hayward, because FOs shouldn't makes moves based on what players, especially free agent players, want.
Then there are people saying he did what was better for him (and his family... family is separate and we can't know and have no authority to say what is or isn't better for his family) but he left slightly more money and the best player on either roster (Gobert) and IMHO the better overall roster to go to Boston. He left a team on the upswing that was looking like a solid bet for top 4 seed in the west. Sure, Boston is almost certainly top 4 in the East. So I guess it's cool to be a big fish ion a little pond?
Anyway, the bad feelings aren't really about "loyalty" it's about the way Hayward did it, that when the news leaked he denied it in a way that he shouldn't have if it was true, and it was true.
