As far as I'm concerned, a dev can take as long as they want to put out content. What I do have a huge problem with is when they make such a huge deal about making elaborate release plans and release dates, with weekly updates and whatever else, and then simply decide to shit on all that.
But let's recap what exactly happened here.
This "series" was announced in October by DSP, who at the time was considered one of the most consistent developers of these HTML games. Then he announced a poll to have the fans decide how it would be released. After the option to release 4 parts over 4 months obviously won because people are stupid and impatient, he announced the grand plan to release episode 1 in December, and then one episode a month until March or April depending on delays.
Either episode one was such a letdown that it turned the whole plan sideways, upside down, and shook it all around, or DSP simply didn't want to stick to his original plan and changed everything deciding to split parts 2, 3 and 4 into just two parts. I can't even begin to imagine how shit episode 2 would've been if it hadn't been stretched like that. That Alexia scene redeemed the whole thing.
But now it's way over a month after the whole thing should've been over and the dev is nowhere to be found. Imagine if he decides to quit, leaving both this and the academy unfinished. All over a stupid spinoff that wasn't even well received.