Rothfuss could re-establish control by saying:

'I'll give you updates once every 4 months on my blog whether I'm made any progress or not', and then sticking to it.

He doesn't. His frustration is understandable, but at the same time he has to realise that the majority of his readers finished his latest book 5 or so years ago and now just check in from time to time to see if there's an update. In the normal world this is a perfectly reasonable request, and normally a complete non-issue. You simply say 'yes I'm making good progress. Can't tell you when I'll be done but I'll give you another update at [x date]'.

Instead they get shouted at by a cantankerous author who, frankly, appears to suffering as a result of issues of his own making.