From the words of Mr. Thomas himself...
"Why no Alto PPT?
There are currently no plans for an alto mouthpiece. The soprano, tenor and baritone mouthpieces were developed purely for myself, not as a commercial venture, because I could not find any existing production mouthpieces that would perform the way I wanted. I could find great sounding mouthpieces but they were not versatile enough for the music I was commissioned to produce so I set about creating something. As I can find plenty of good alto mouthpieces that I like, including Selmer Soloist, RPC, Jody Jazz, Brancher and many others, it has not been a priority for me to “reinvent the wheel”, especially as PPT mouthpieces are completely non-profit making, I would find it difficult to find the time. One day…"
Greg S.
P.S. Pete's mouthpiece of choice for alto is a RPC.