Yeah, that's the settlement rules. We were talking about PDT in a margin account where you can have restrictions slapped on your account for violating the rules.
PDT restrictions do not apply to a cash account, so you are perfectly free to day trade your account right down to $0 for the simple reason that you are only hurting yourself.
PDT rules apply to margin because now you are using other people's money so they want you to whoa it up a little bit.