Hereward, are you going to add in ideology-based planets? It would be great to see a source of ideology points that doesn't require continuous colonization.
So far this mod only adds natural planets. I have given it some thought about planets that generate ideology points.
In multiplayer games humans will have the sense to colonize ideology planets that favour their game plan but the AI, I doubt, is programmed for that. They will probably colonize any and all the planets regardless. I know nothing about modding the AI.
There are already buildings that generate ideology points available from the ideology tree so generation of ideology points does continue when the initial colonization phase has completed. For the AI this is relative to it's programed decisions when previously colonizing planets and building ideology point generation improvements, rather than randomly colonizing ideology planets.
If I where to tackle your request I would do so as a separate mod as it may appeal more to multiplayer gamers rather than single player/AI gamers.