I agree.
Energy is just a number to talk about, it has little to do with effects on animals especially when talking BP firearms. Forsythe tells us that a hardened 15 gauge ball would shoot though an Indian elephant's head from side to side with "5 drachems" of powder. In "Pondoro" John Taylor related killing 8 Rhino and African elephant, "13 good bulls", with a percussion 10 gauge single smoothbore with 6 drams of BP (165 gr) and hardened balls. His remarks at the end of this story are something more people should read:
"Men with their modern breech-loaders and repeaters are all too much inclined to sneer at the muzzle-loader. But a good muzzle-loader, properly handled, is a very deadly and effective weapon--provided its limitations are fully realized."
He killed them all with lung shots, killed all he shot. I doubt that the ME of the load would impress the modern shooter as an "elephant gun" but it worked perfectly as he used it.

Dan