You, sir, win the kewpie doll for getting something that is supposedly unobtainable on this map. I recently found the code that actually spawns these critters in the Nether, and you are correct that you can obtain a blaze rod in the manner you've described.
With a little bit of decyphering, I might even be able to publish the formula based on the Skyblock seed for generating the fortresses... and I'll admit I hadn't thought of doing that before you mention it on this particular map. There definitely are several resources you can get with villagers that are otherwise unobtainable on SkyBlock.
One that isn't documented on the wiki but is possible with the redstone is to make an obsidian generator by pouring lava over redstone wire. You can either "build in place" or get a diamond pickaxe from a villager to use it in other ways as well. It would be nice if you could get some diamonds to make an enchantment table, but that isn't on the map. You can, however, make multiple ender chests that way though