This is total B.S. This guy is in maintenance. He knows better! Any mechanic will tell you all of these vehicles have fuel filters. Anyone who has ever worked with diesel (which is very close to jet fuel or kerosene) knows water is commonly filtered out. If there is too much water the vehicle will "run out of gas". This would happen before take-off if it is "contaminated" to the extent he seems to be eluding to. Also if it had been rejected before it is more than likely they did not have the means to filter it at that particular installation. Perhaps they did have the capability where they were ordered to deliver it. I doubt it was throw-away, that makes no sense.
What would happen if helicopter fuel was contaminated with diesel fuel?