Ah, I was thinking of things the other way around initially: “If I’m already limiting who can send me a personal message, I probably don’t want people who can’t send me a personal message to direct message me on chat.”
In your case, are there cases where would you want to be able to allow a subset of people people who can PM you to send you direct messages on chat? Or would you always want to stop everyone from being to be able to send you direct messages on chat?