Well, yes, but that's kinda my point. If you don't patent, you get exploited, like how the discoverers of insulin synthesis decided not to patent, so companies patented similar, but not exact methods, and now it's incredibly expensive. But, as you said, if you do patent, there is still a risk of exploitation if the patent holder sells to an exploitative company. However, that exploitation is still less likely than when not patenting, so I support the practice so long as patenting is still possible.
I worked at a small nonprofit back when genes were still able to be patented; we mostly studied the condition Pseudoxanthoma Elasticum, and held the patents to a few of the genes associated with it. However, we still allowed people to research them freely - we only patented them to prevent a company like Myriad Genetics, who had been patenting genes so that they could sell expensive genetic tests, from patenting it instead. We celebrated when genes were no longer able to be patented; I imagine that the researchers working with golden rice will do the same if we're ever lucky enough for GMO's to no longer be able to be patented.