In a mugen tank if the clunk filter is removed, you will only get about 5-6 min run time, if you are lucky ( i lost one on a mbx5r)
If Anything, the metal could have been sucked to the filter and clogged it. There is NO way these shavings could get through the clunk filter AND then a ext filter.
I would bet his motor is fine, It just couldn't get any fuel.
broken fuel gun/bottle is a long shot. What type of fuel does he use? Maybe it comes in a metal can?
An accident(such as fuel gun) seems like REALLY long shot.