The reality of abbatoirs is that killing is not humane. Disagreeing over methods by anyone who eats meat is hypocritical or, at best, based on ignorance. It just seems like attempted political/religious point scoring (eg the Daily Mail being outraged at Halal slaughter - like they give a ****).
"Each day around 100,000 cattle, sheep and pigs are slaughtered for food in the UK, as well as 2 million chickens a day. No one ever asks whether these animals are being slaughtered humanely. Sadly, often they are not, largely because animals are hustled through modern abattoirs at such great speeds that it is very difficult to safeguard their welfare.
...
CIWF Trust believes that one of the principal problems (which will be referred to at various stages of this report) for cattle, sheep and pigs and for poultry is the danger of animals regaining consciousness during bleeding-out."
- Compassion in World Farming report.
https://www.ciwf.org.uk/media/5161334/animal_welfare_problems_in_uk_slaughterhouses_2001.pdf