Just make your own and stop being such a pussy about it, the chances of making a duff BIOS are very very low indeed, especially if you use XBtool. And if you do make a duff BIOS and have a bad flash who cares, its easily fixed and not the end of the world.
And they dont host them because there is no need to host them, people make their own, all you need is a virgin BIOS, and now with the new features of XBtool the BIOS doesnt even need to be that anymore.