They aren't saying they guarantee 100% uptime. They're saying they'll pay you for any downtime. It's literally the 3rd paragraph:
> 1.2 Penalties. If the Service fails to meet the above service level, the Customer will receive a credit equal to the result of the Service Credit calculation in Section 6 of this SLA.
(Most people I know consider them meaningless marketing BS that's really just meant to trick people or satisfy some make-work checkbox)