Floor slamming was surely already contrary to animal cruelty laws and ought to have been addressed. But carbon dioxide may or may not work well; for odd reasons it can fail. Cows are often slaughtered with captive-bolt guns; why couldn’t piglets be put out of their misery the same way? These guns are air powered and unlikely to fail but technically they too are blunt force trauma. The baby has been tossed out with the bath water.
The company said that blunt force euthanasia was approved by the veterinary association for pork producers. That doesn't make it right.
I'd argue whether the technique was blunt force 'euthanasia.' They didn't even slam these piglets into the ground unti they were dead.
They would slam them two, three, or four times into the concrete, then toss the living piglet onto a pile to die.
Like you, I don't know the answer. As for captive-bolt guns, piglets squirm more than cows and the target area is much smaller.
However, there has to be a better way than the way shown in the video. The company's essentially admitted that practice can't continue once the public knows about it. Of everything shown in the video, it's the only practice that will be discontinued.
MUCH smaller target. Much more likely to miss and cause additional injury and pain. Floor slamming LOOKS barbaric, but it is less prone to such error. Kind of hard to floor slam a cow (or calf).