I was assuming "masks are mandatory" meant everywhere, but you are right: we don't know that yet. Has anyone seen the actual agreement?
With the wording of the "release," it could be that Disney is actually being reasonable and requiring them only where most experts seem to say they might be minimally effective: in enclosed areas where social distancing is not possible. That is doable. After looking at the release about the union and realizing that "mandatory" cannot possibly mean everywhere at all times, since people have to eat and drink in restaurants, swim in pools, etc., this could be a more reasonable plan than many have interpreted.
If masks are only mandatory for transportation, indoor queues and rides, and shops, this is possible. That way, if kids are required to wear them and become very uncomfortable and panicked from wearing them, the kids (and adults) can easily be removed to an area where they can take a break from the mask.
I might even consider just visiting a resort and taking my daughter to the pool and eating in various restaurants- if masks are only required in shops and in lobbies. But walking around AoA with a mask where no one is in sight, then having to sit in a mask as I sit in a lounge chair at the pool- that would be ridiculous.