I understand that RH is not a MM. So then why does RH have to manage its risk from the holdings of it's own customers? I am not a finance professional but I th

I understand that RH is not a MM. So then why does RH have to manage its risk from the holdings of it's own customers? I am not a finance professional but I thought RH is just like a custodian and facilitator of trades. It's not on the other side of any of these trades. It never holds any positions. Why does it have to manage its risk and why does a GME event create extra risk for RH? I thought this kind of risk is only for the MM's like Citadel.