Not that it matters to people outside of Japan but the SASUKE Mobile Site (315 yen a month!) will be shutting down on August 31st. For now it looks like the 筋肉モバイル (Kinniku Mobile) site will stay up. It's the more active of the two, as it covers the Muscle Musical and features new content on a fairly regular basis.
It's possible that Monster 9 is pulling the plug too quickly. There is nothing to promote between SASUKEs so naturally there won't be much interest in the site. Unless they want to devote a site to stalking the All-Stars, New Stars and Lee Enchi they don't have much to work with. Seeing the All-Stars at some event is nice but pretty meaningless in the long run since it's just generating interest among those who are already fans.
Frankly, I'm not that surprised that the site is going down. Monster 9 tends to have ADD when it comes to marketing. SASUKE Matsuri? Only held once. The SASUKE Library app? Only for 23. Two SASUKEs have gone by since then. And it was pretty useless. SASUKE Challenger? Once you finish it there's no incentive to keep it on your apple device much less play it again (unless someone figures out how to get the Extra Stages). The SASUKE website? It hasn't been updated in months. Poor Yuuji doesn't get to have his picture up with Nagano and Akiyama.
Just get a weekly TV show already.