No, they mean don't use the nylon push rod, you will still use the nylon guide tube that runs through the fuse. It's usually a grey tube, largest diameter, that the nylon pushrod would go through, just use a metal pushrod instead of the Nylon rod that comes with the kit, everything else is the same. I'd use 2-56 rods (what I used on my 4*), 4-40 is overkill in my opinion on a Midstar and will only add more tail weight. It is a pretty straight shot, your right, but the longer the rod is the more flex you'll get, especially while flying with wind resistance against your control surfaces pushing back. The guide tube will keep them from flexing like that. My LHS sells individual pushrods in a standard length (yours may as well) or Great Planes sells a little package containing the Rods, Guide Tubes, Nylon clevis's and other little tid bits in "36 inch length (which is what I used for the 4*).

Sullivan also makes the equivalent thing called Gold-n-Rods...you can go to Tower Hobbies and search "Push Rods" (make sure you note the length and don't order something to short, you can cut a rod shorter easier than you can stretch it longer). The sets usually come in lengths of "36 and "48....I think. Just cut the rods the length you need.