[mego]

My puppy class I go to has us ignore spats between the young pups too, but none get super intense, sometimes some get too bitey and another dog will yelp and that is all the correction they needed. If yours are being too mean I think it's understandable what you did, but I do think they will NOT learn how to play gently until you let them roughhouse and make mistakes upsetting other puppies and realizing too rough ends the game, and it's better to do that while young. If you continue to pull them away from dogs while young it will make it much worse when they're larger

I dont like the sound of the other aspects of your class though, also if you were concerned about your puppies being too rough the trainer shouldnt say "no matter what happens dont interfere" they should address your concerns and offer constructive help, maybe a different kind of socializing for your guys