I would see 2 ways to do so:
You can replace "CurrentUser().Admin=False" with "(CurrentUser()='UserA' || CurrentUser()='UserB')". Use "Formula Options" to replace 'UserA' and 'UserB' with their usernames.
You can also define a UserGroup containing the authorized users and use the syntax: (IsMemberOfGroup("Authorized Users group", CurrentUser())
Let me know if that make sense.