It is simply harder to sabotage if the wires are underground and cannot be readily seen by hostile actors.

This statement is not correct. It is the topic being discussed. Fiber network are more vulnerable than satellite networks. It takes specialized weapons to take out a single satellite link. Any idiot with wire clippers can take out a fiber link, and it happens all the time. Fiber networks are more difficult to replace at scale than a satellite network, and individuals links are more important to fiber network than they are to satellite networks.