You can't really influence the AI's decision making as far as I know.
But you can configure its Equipment in ShipDescriptions.xml as Oxy said.
Try to find what ship descriptions to edit via some help in create_flight_2.script
That script contains many huge tables which resemble available Flights and their Ships INSIDE the ShipDescriptions.xml
Ship Descriptions are XML Entries which contain the Ship to use (Carcass from Carcasses.xml) and then some Equipment (Modules from Modules.xml including rockets and stuff)
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