He's saying after the 90 days is up, you'll still be vulnerable (because your SSN/DOB won't change). Better to just freeze indefinitely and lift when necessary unless you know you're going to be opening a new account soon.
I get that - I was just sharing the information about a Fraud Alert, which unlike a "freeze" is free and allows you to still apply for credit without lifting the alert.
I think vkou is implying you need to do this every 90 days (which from my understanding, is what Life Lock does).