Alas, they can still add and remove such a policy, or tuned variants thereof, at their own discretion at any time. And have done so in the past. And would be keenly motivated to do so in the future.

So them not-having-the-policy on a particular day N isn't really much comfort for those who'd like to build functionality for day N+1, when Facebook may have rewritten the rules to its own advantage again.

Will they contractually commit to a policy for a specified period of time?