You gotta ask yourself this question. How many "old timers" used blades with rust on them, and I'll betcha none of them got sick from it.
Better question. How many people use blades with rust on them right now? Ask Jeff Randall and he'll tell you that the vast majority of knife users around the world cut with rusty blades. And NONE of them get sick from using them.
I often use blades with rust and/or patina on them for food prep. Besides my INFI blades (which are not too rusted yet despite that the coating is very weared), I use a custom knife in O1 steel (made by myself) which got rusted fast and a Cold Steel knife in SK-5 which also rusted fast.
The taste and smell of food is usually affected. But for health there is absolutely no danger. This is also a recommended emergency iron food supplement: to put some nails (or other iron things) into vine or an apple and then eat it. Rust doesn't make you ill unless you exagerate while eating it.
