What The Dude and Marko said! Furthermore, as long as the arm movement causes no rotary issues, well then......
This guy skis kind of ok, I guess
...but to each their own
It may have to do with the fact that the cue for getting forward that I see currently in the CSCF is the "forward pole plant", which does require a swing of some magnitude to be effective I guess - and creates muscle memory. I see the same, a lot on the WC, but in SL you can't quite help it, can you in fact that may be the other reason I see it a lot: it mimicks clearing the gate - helps with that muscle memory?
When I picked on Helluva's pole touches was not because of no arm movement, but because they could be more consistent and possibly a bit earlier, especially in the second part of the GS video... When they happen, their form looks good to me, like the rest of the skiing there.