The guards on the USS Cole also had no clips. That’s why they couldn’t shoot the Zodiac as it approached.
We they holding M1 Garands?
That's correct, at least in part. A few were armed, but only with sidearms and only with two rounds each - hardly the stuff to repel a suicidal attack. Both crew served weapons, forward and aft were unmanned as well. Lastly, even if they had been armed appropriately, the rules of engagement were such that it prohibited the sailors from firing preemptively.
While the official investigation cleared the ship's captain - he set force protection using the directed guidelines - the report clearly identified that those same force protection guidelines were woefully inadequate.
There are plenty of people for many years that have vocally stated that US service men and women should never stand watch with unloaded weapons, except of course in training, like boot-camps. But, common sense and practical responsibility continues to give way to political correctness. Command is more afraid of accidental discharge or lost weapons with ammunition than they are of actually protecting the principle - the principle in this case actually being US service men and women.