Do you have some evidence to support that?
From the Overwatch FAQ:
Q. Will Mac users be able to participate in the beta?
A. We’re developing Overwatch for Windows-based PCs only
The update was released yesterday, yet it still isn't showing up on either my iPhone or iPad. Is something weird going on, or are Apple just making it available to groups of people over the course of several days?
It looks like people in the OS X seed program are getting invites for this first, or is the iOS seed program different from the public beta, like the OS X one?
This is one of those rare occasions when having the Macintosh version of the game not ready at the same time as the Windows one is a bit of a blessing.