mines and fighters

[Alneyan]

If there are still mine layers/mine sweepers around, then the technology has not been disabled. By the looks of it, you have removed the mines hulls from the game, but the technology remains as the components are still available for the AI. You will want to disable "Mines" in the technology options at game setup, as it seems to be the problem here. (Unless the AI is somehow able to build disabled components)

PDC is mostly useful to hunt down fighters and seekers, so if you remove fighters, you will need less PDC (and so the AI should build less of them). Toying around with a lot of seekers in such a case would hurt the AI however. PDC is also able to target satellites and drones, but the former is not too common while I am not sure if the AI can even use drones. At any rate, your main weapons will likely be your main bet to take down drones, as you would need a lot of PDC to destroy a drone fully loaded with shields/armour/warheads.