In a comment shared by r/Apple moderator @aaronp613, Reddit cited its Moderator Code of Conduct and said that it has a duty to keep communities “relied upon by thousands or even millions of users” operational. Mods who do not agree to reopen subreddits that have gone private will be removed.
If a moderator team unanimously decides to stop moderating, we will invite new, active moderators to keep these spaces open and accessible to users. If there is no consensus, but at least one mod wants to keep the community going, we will respect their decisions and remove those who no longer want to moderate from the mod team.
They might have to contract some janitors temporarily.
They can afford it. It will keep things running smoothly until volunteer mods are sourced.
Also, the reason they are shutting down third party apps is control. Bottom line is money, but indirectly. They want everyone using their app or their web interface so they can harvest the most data and sell the best ads.
My guess is, that they‘ll wait as long as possible to pay mods. This would set a precedent for the whole platform.