"major security risks" as in Terminator style robot overlords, or (to me more likely) they enable people to develop exploits more easily? Anyway I fail to see how it makes much difference if the models are open or closed, since the barrier to entry to creating new models is not that large (as in, any competent large company or nation state can do it easily), and even if they were all closed source, anyone who has the weights can run up as many copies as they want.