Just wanted to give a warning to people about this -- I'm not sure whether it's just an issue inherent to the mod itself or it conflicting with another mod, but DIY Planets broke AI core drops from remnant fleets and stations for me, such that they never dropped under any circumstances, even the guaranteed drop from killing a station.
So I think after doing some of my own testing with the mod I found out that it doesn't remove drops or influence them, even without the mod the guaranteed drop didn't occur mind you I play with a very large mod list and I imagine you did the same, good news you can still play with DIY planets and other mods you have and get drops from fleets, altho im not sure if the percentage rates were normal or I just have imhumane I only got an Alpha after killing maybe 40 fleets over 3 hours (I put on god mode to test)which resulted in 26/21/1 of G/B/A.