The reason for this executive order is probably that government communications is increasingly occurring on the public internet, and, just like how many hosting services (be it AWS, Linode, or otherwise) provide dedicated communications links between data-centers, the US Government will probably be establishing its own fiber infrastructure.

This is probably a stop-gap before wiring up the entirety of the US mainland with dedicated fiber connections, and hopefully the USG will release their clutches from the internet's core infrastructure afterwards.