It's in the context of "All you fellow group members get a move on and get your IMC ratings while you can.
An IMC rating involves applied instrument flying which you as a CRI are not qualified to give. A FI Course involves teaching IF but not Applied IF. A FI may teach the basic exercises of the IMC course but only a FI without the applied IF limitation, or an IRI can teach the approaches. A CRI can teach nothing towards this rating.