Apart from the weirdly misleading subject line, the advice in the mail is really misguided IMO. If your ISP fails to update their trust anchor, disabling DNSSEC entirely for your domain will indeed let you access it again, but it won't do anything for other sites that you can't access, and it rather defeats the purpose of enabling DNSSEC in the first place if your first troubleshooting step is to turn it off again.