I had a good laugh imagining that scenario you describe. An Argus and a hisser having a hissing contest.. hahaha.
It is kind of surprising that the Argus wasn't that interested in the hisser, but not that surprising. I have noticed that some individual monitors do not seem to like the 'taste' of hissers. Lobsters seem to be much more widely accepted. They can climb well, and can even climb glass. They can be contained with a slippery substance as a barrier. Many recommend Vaseline, Teflon or other substances I consider questionable for this purpose, since the roaches are intended as feeders for valued animals. I prefer to use a substance that is very safe if consumed. I use a thin sheen of lard, a few inches wide, near the top of the container. If using a plastic tub that is somewhat textured, you can make the barrier more slippery by applying a ring of glass tape first and then applying the lard to that. I never have any problems with roaches escaping from their homes.
I also raise Blaptica dubia, which are larger than lobsters and seem to be very acceptable to monitors. They are very poor climbers, so they can be easily contained.
Cheers