If he would have called it anything else but Twitter and stated it is theoretical or a hobby project or something for fun, I would be fine with it, but don't mention Twitter anywhere near because it has nothing to do with Twitter.
A post like this without Twitter in the title isn't nearly as provocative, and would probably have died in /new. It's because of the authors decision to scope out a Twitter clone that we're having this discussion!
It has nothing to do with Twitter, except if you described the features of the project, the vast majority of people would say "oh, its like Twitter?"