Yeah, in my opinion those instructions are generally BS. As far as I know, Fromia stars are organic film feeders. I don't know that you'd be able to stave off starvation by adding shrimp, mussels, or flaked food (that sounds like a ridiculous set of options, by the way, since there is almost nothing that you could feed all three of those things). People who keep them more-or-less successfully usually have a lot of glass and a lot of live rock surface area.