Hey Killian, here is subzero, now, plain zero.
I can't imagine they had TV in prison, and he never had the chance to watch an episode of the show, although, Richard's character did know of Killian.
The show was on-air before Richard's story line so there is a chance he already knew of the stalkers.
But, as you can hear in this sound-byte, SubZero is introduced in detail so Richards could have simply heard/seen it then.
Related: In the book, Richards willingly goes to the network which is where he learns about everything (including the stalkers) beforehand.