Lucky the land is so flat and the water wasn't flowing too fast. I wouldn't have liked his chances of closing that if the water had been running downhill with some speed.
Looks like a very flimsy breakwater before the breach: sand & soil will just wash away again. Bits falling off left bank as he tries to fix the other side.
Should had hauled in more rock on both sides before trying to breach the blowout! Then use two dozers on each side. To close the hole. This way you don’t weaken the dike even more.
Oh you are right. Except, if you bothered to read the header. Colorado river, canals. And looked at the background. You might have figured out this is sw Arizona. rocks are quite scarce here. And waiting for that second dozer would have wasted time. Canal breaks are not planed in advance, hauling in rock and having dozers standing by is not realistic