I think the team legitimately doesn't know if he'll be back this year. They obviously want to think long-term, and want to avoid at all costs rushing back only for him to get re-injured. Given these two points, it makes complete sense that everything they say would be oriented towards not raising expectations for Hayward to play, so that the player himself doesn't feel that undue pressure. That's why they keep saying their base case is that he won't play this year, without completely ruling it out.
Another factor: As we all know the team can still use that injury exception to sign/trade for a player, even if Hayward comes back. But could you imagine if the league granted that exception, and even before the all-star break the team started publicly talking about him coming back? That would not be a good look. This is is another reason that the team needs to treat the prospect of Hayward's return this year as gravy, if for no other reason than it wouldn't want to needlessly raise the league office's ire.