Maybe wait to play the episode to see how mini it is, and also it's only been 60 days since last release. How many updates do you 4 want a year? 4, 10, 20? What is reasonable. Start with that, then complain when the agreed upon parameters are not met. IMO 60 days is nothing to complain about. Honestly, the proper time to bitch is after release, that is proper bitch etiquette, when you have all the information.
P.S he could probably release each side quest in 2 months. It depends. It could be he thought this was going to be a mini update, and it ended up being regular size, if there is just 10 minutes of play time I would understand anger, but if it's the same size as last update then he actually did it faster this time. The extra length to release the update also makes sense since this whole update was unplanned apparently, when things are unplanned it takes crush longer. So, proper criticism is he needs better planning of the overall story.
So it could be 6 months for all side quests + linking the backstory 4-5 months, +1 additional update, = 1 year. Still not a lot done, but NOT horrendous compared to other devs. If it were up to me I'd want the whole game completed tomorrow, preference wise... but what is actually realistic?