It is possible to force AI put more than two types of weapons. For example, AI put 2 "normal" weapons and PDC using "point defence" ability type.
To extend it to other weapons, you must assign some bogus abilities normally reserved for facilities, like "spaceport" and use them as tags for specific weapons.
Take a look on Proportions mod file for examples.
As to unmoded SEIV, no, it is impossible
