Reasons don't matter to the program. It looks at what is in <race>_AI_Construction_Facilities.txt under the homeworld construction queue entries. Edit the default_ or the racename_ Version and you'll get what you ask for.
I tried that. I modified the Default_AI_construction_facilities.txt file to increase the radioactive and organic facilities from 1 to 2. It doesn't work! The race I am playing is Terrain, and it doesn't have any special construction text file.