Stalled? It just had an update.
It's also in the 3rd version, under development, which came just a couple of months after the 2nd version had been released. He could just have released ST2 and keep it at that version for 3-4 years.
Instead he immediately started development ST3, which had frenetic development in the first months, and has been completely stable for a year or more (I know, I use it everyday, along with several plugins).
And in the forum he even mentioned ST4 base libs he is preparing a month or so ago.