Seeing as how one primary cable had already faulted and had a previous splice in it, there is a very good chance that that is the reason for the second burnout, hence possibly doing damage to the other cable again, I would'nt care what the company said it's a matter of working safe and if they wanted it fixed I would have de-energized the other cable, tested for dead and grounded and then spliced it.There is no reason that I can see for anyone to want you to do it any other way, I can only guess that by killing the other cable it was going to take some lights out, but so be it, it's not like it's going to take a long outage to do a URD splice anyway. Sounds like you know the right thing to do,stick to your guns and keep those apprentice's safe.