You know that a sidewinder cannot fit a PA do you ?
Are you sure you didn't face on of these railwinders ? Those are nasty bugs, especially when met in a swarm.
But I tend to agree that NPC's loadout all haying rails (I saw those on a T9, for real XD). is a bit ridiculous.
More so when they spam them to no end with a total disregard for heat generation.
(try firing a pair of C2 railguns 4-5 times in a cobra like NPC's do...)