From BnG Rules:
"Girders may be used for bouncing purposes only. Destroy the girder before continuing if placed incorrectly."
Johnny is correct, the 1st girder is used for protection (not allowed) and stops him from being plopped, he should tele somewhere else, if no hides left, not 5150's fault, should make a higher map, or try and hit more consistently so the game doesn't last long enough for a whole part of a map to be destroyed.
The 2nd girder stops the worm on the left from being hit easy with zooks and low angle grenades, (again, protection, not allowed), and also ruins the the possiblity of using BackBounce grenades to hit the worm on the right.
IMO the game should be replayed, but obviously a MOD will have to handle this.