Fyi, I installed Scribus so I could test. And I have the same experience, opening the SVG file in Scribus.
At first I thought maybe it didn't matter that the image was scrambled, since in Scribus, all you do is change the color settings. But I followed the tutorial you referenced all the way through, and the image does not come back together in the end (as I thought it might).
My best guess is that it's the incompatible features which Scribus alerts on, which is causing the problem. And I might also guess that filters are at least part of the problem.
But I'm really guessing.