Couldn't agree more.
The amount of fish sharks eat is tiny compared to what we take out of the ocean, so that argument about "protecting commercial fishing" is non-existant. Most sharks that size are after things like seals etc anyway. Long-line commercial fisherman are one of the main killers of sharks unfortunately. Like FishHeadRic says, removing a predator from the eco-system is never a good thing, and often many other species die off as well as a result.
It would have been much better to have cut the line and let the shark go. Sheesh, if you want to see a MAKO, and alive at that, go to an aquarium.