Presumably GP means they will deploy their on GitHub Enterprise server instead of using github.com.

GH Enterprise is run on your own servers, so you'd theoretically run it right in the office. It may not move the needle on actual downtime, but there's some control in the downtime - if the LAN is out no one can work anyway, and upgrades will only happen on your business's lean days, be tested out with the teams that have an appetite for experimentation, etc.