When this strip came out, I was not yet reading Freefall. I'm a die-hard fan now, and at least three other Talk-Polywellers follow the strip. It is surprisingly technically rigorous in science and fusion. http://freefall.purrsia.com/lastthree.htm
Read the fine print on Dr. Park's writings and I think you'll find neutral particle beams, and they may be used by Tri-Alpha and a couple of the other efforts as well. These were not part of Dr. Bussard's original design.
Unless tritium is being used as a "starting fluid..."
On a more serious note, Polywell is little known in the sci fi community as far as I can tell. When that strip was written (how long ago now?) The artist didn't know about Polywell. Tokomak is the default for the mpst part, so why not?
I'm still looking at Polywell for a few places in my sci fi, but Mach effect is a big thing and so Mach generators are generally used by the big players.