Right click huh. I guess someone had to have problems with something like that at some point.
I still don't understand the purpose of the "Guard" and "Sentry" commands. Ships with these commands do nothing until a foreign vessel comes withing range and then does more nothing? In the real world, the purpose of a guard or sentry is to challenge any unauthorized person who comes near.
I don't find them useful but I'll try to explain their value. Have you noticed that after you move a ship (so it has no more movement points this turn) that the game will automatically select another ship? Well these commands prevent you from selecting the given ships until the triggers are meet. Not hugely useful in my opinion as they are missing a command to make a complete set.
For me, the lack of a "fortify" command still sometimes results in a loss of starbases. The guard command does good until an enemy ship shows up, but sometimes I try to change/cancel the orders of another ship only to discover that I instead gave orders to a fleet protecting a starbase (and of all times, its when the enemy is close enough to attack next turn).
In case you don't know, starbase defenses are not worth it in this game. Anything beyond whats needed to survive against a random tiny is either a waste, or a short lived advantage. So thats why you need fleets to protect them.