His counterargument is not convincing in the least.
[-] Blingdom suggested:
Ignore them, and wait until it's night. Throw a rock somewhere else to distract them out of their guarding positions and enter the door.
It's already night. Besides, as everyone knows, dwarves don't need to sleep.
[-] Poligrizolph suggested:
He's lying. Shove the dwarves aside and go through the ancient door.
You just shove them out of the way without any subtlety whatsoever.
"Hey! You're not allowed in there! You need to answer our cool riddle!"