We cannot know whether your piggy is neutered, and also as a UK based forum we would not routinely know Petco's policies. It would be unsafe to rely on what you have heard unless and until you have proof of a neutering taking place.
How old is he? Boars are usually only neutered after they are 4 months of age once the testicles have descended.
If he is under four months of age, then his testicles won't have descended so they would not be visible, thereby falsely giving him the appearance of being neutered. However, any unneutered boar over three weeks of age is fertile, so it would be best for you to immediately separate the boar into a separate cage immediately and put the sows on 10 week pregnancy watch.
You can see a vet to check whether he has been neutered.
If he hasn't, then he will need to continue to be kept separately to the sows until he has been neutered and had the six week post op wait to become infertile before being able to be bonded back in with the sows. However, if the sows are pregnant, then you would know by that time and would have to look to make alternative living arrangements depending on the sexes of any pups