Assuming Hayward is in fact being listed as a guard AND knew that would be the case during the summer.
It doesn't seem far-fetched to me that the all-star game at least played a role in his decision. We already know that making the all-star game last year was a huge priority for Hayward, as evidenced by his 2016 offseason meeting with Dennis Lindsey where he hounded him on wanting to make it.
Also, we know at the very least it was on his mind based on this quote when he talked to Zach Lowe after his decision:
"The All-Star thing is going to be hard no matter what division you're in, but certainly with the amount of stars that are in the Western Conference now, especially at the forward position, too. It's loaded, and you better have a really good first half of the season if you want to get in [to the All-Star Game]. "