He did say he would be bringing the rats inside for winter.

TEchnically the abuse would be if you mistreated the rats, or deliberately exposed them to detrimental conditions. Neglect would be covered by lack of food, water or shelter.

Your description doesn't sound like abuse or neglect. If your roommate has a specific complaint,(ie the possibility of cats) then you could see about remedying that specific concern.

Feeding dog food isn't ideal, but there's been plenty of rat breeders who used dog food. Having them exposed outdoors is also not ideal, but if you have them protected from sun and rain, and the temps do not get too hot or too cold, then it's okay.

My main concern would be exposure to cats or dogs. Even if the cat can't get directly to the rats, they can stress them out by attempting to, climbing on the cages and clawing at them, etc. Rats under stress can injure or kill other rats or themselves in panic. Also, they're exposed to fleas etc and to anything any neighbor sprays for weeds or pests(drifting in on a breeze).