Oh, for God's sake, no wonder I kept getting owned so hard in Maridia! I mean, I'm probably a better Metroid player for it, but I guess I should play through it one time the way it's intended to be run, just so I have a better sense of how hard it's actually supposed to be.
Thanks for the heads-up!
mockballing does allow a big sequence break though, which I guess is what you assumed was the intended route.