Honestly i get that you are angry/disappointed on a personal level. But its pretty normal reaction from reddits side. You were not cooperative to their request to open up the sub so they searched for someone who would do it.
I dont want to defend them, i allready cleared my account over there but from a business perspective its a normal reaction. If your employees (even if they work without payment) dont follow your instructions you search for someone who does follow them.
And the new mod might be a prick for backstabbing your protest but thats just a opinion. If there are enough users who want to keep using the sub, regardless of reddits shitty behaviour, its ok to reopen it and none of the old mods has a right to hold it "hostage" for their protest.