To open or not to open?

Some time ago I ran a session of a homemade sci-fi RPG with some friends. I helped them make characters and I sent them on their first mission.

They were to land on an ancient machine planet and search for useful technology. As soon as their shuttle landed, their orbiting mothership was attacked by hostile aliens and destroyed. Shortly after moving into the ruined city, they noticed multiple alien dropships landing in places all over the city. The party continued through the ruins until they encountered a group of small aliens with a large box. They quickly dispatched the aliens and went to investigate the box.

Mole: I'm going to open the box.
Slick: Don't! It could be a bomb!
Mole: We don't know that. I'm going to open it to see what it is.
Me: You pry open the side of the box and are faced with a large, curved metal panel wth no discernible features.
Slick: It's a bomb!
Mole: Maybe. We don't know what it is for sure.
Slick: It looks like a bomb.
Mole: It could be a robot.
Slick: If it's a robot then it might attack us.
Mole: I could reprogram it not to.

They debated whether to continue investigating the box for a whole hour (RL time). The other two members of the party moved to a safe distance and waited. I finally got tired of waiting and got them to make persuasion rolls against each other. Mole won and got to pull the thing out of the box. It turned out to be an automated sentry gun which almost killed him while he tried to dismantle it by hitting it lots. I later discovered that he intended to turn it into a fast road vehicle of some kind.

Also in the same session:

I idly roll some dice behind the screen.
Slick: What did you... Everyone hit the deck!
Me: You can't use out of character information in character.
Slick: Oh.
Me: By the way, snipers fire at you from rooftops.

Some encounters later, Slick acquired fatal injuries after trying to climb up the back of a very angry cybernetic monster and stab it in the back of the head. When creating his new character...

Slick: Can I have a pair of swords?
Me: What sort of swords?
Slick: Twelve foot bone swords, made from the bones of a space dragon that my character slew with his bare hands.
Me: There are several problems with this. One: There are no such things as space dragons in this setting. Two: If there were space dragons, how would you kill it with your bare hands in space? Three: Twelve foot swords?
Slick: Oh, what about imitation space dragon bones?
Me: o_O
Slick: And I can make them only ten feet long if you want.

Most of the combat had been firefights with futuristic assault rifles and laser cannons. He wanted swords (and rather silly ones, too).