Not according to what I've been taught.The preview actually says "virtually unheard-of", which is pretty close to "Rare".
Solomani & Aslan, p. 87 mentions two entire clans that make regular use of psionics. In authorial voice, not viewpoint writing. The rules Bill quoted says that psionics are rare because most Aslans don't get tested, not because they're not capable of being trained. That is most definitely not the same thing as being "virtually unheard of". In fact, it's very much "heard of even if not met any".The preview then goes on to mention a few known psionic Aslan, but claims they were either mythical or mutations.
Hans