What makes you say we were unprepared? We have been deleting malicious crates for a while. This is the first time those crates have wormed their way into an actual real crate that people use, but most of the playbook here was the usual one. We take a snapshot copy of the crate and then purge it from the system.
The security page thing is because the rustsec maintainers were not around or a part of the response as it was occurring. It's pretty normal for a security advisory on rustsec to take some time to merge. We should probably get everyone on the same page about when people not on the rustsec team can merge security advisories, because I do agree that getting them merged quickly is important sometimes.