I disagree with you. If you really care about animal welfare, you should look into flexitarians and support it.
The definition of vegan contains “as far as is possible and practicable,” and I think this contains some occasional slips. When a person’s health is failing, I think it’s perfectly okay to consume animal products for a short time and reassess what went wrong. Fixing your health and well-being falls under what is possible and practicable.
If YOU can go 100%, that’s great, and you should, because that is what’s possible and practicable for you. If a person goes vegan and has a leather belt, I think it’s fine to continue using that belt until it wears out, then buy a new, vegan belt.
Some people can’t (or at least not yet) be 100% vegan because it isn’t practical or possible.