"Dispensible" was probably a poor word choice. I wouldn't want to initiate a tank with discus, for example. It's simply a case of being practical; you want those first fish to be hardy and not worth a fortune, just in case something goes wrong. It's not as if you're offering them up as a sacrifice to the gods!
That said, taking a 30g tank (that is correct, I think?), containing active filter material, and putting in a couple tiny fish for a few days while monitoring the water doesn't seem to me to be particularly cruel or likely to cause any significant level of suffering.
My normal approach to starting a new tank begins a couple weeks prior to getting the tank. I put ceramic material into a mesh bag and drop it into an established tank. When I start the new tank, I drop the mesh into the filter and add a couple of whatever dithers I plan on using. I keep an eye on things for a few days, and if everything looks ok, I install the stock. I've never seen ANY problem doing it this way, and have never observed ANY indication of "suffering". Nonetheless, I wouldn't have put my ebjds in the tank immediately, because they cost a bloody fortune! Now if that pragmatism offends anyone, frankly you'll just have to live with it.