This is similar to the forced feeding situation when there were hunger strikes at Guantanamo Bay. A clip was circulating around of a young boy happily demonstrating inserting his own feeding tube and a lot of people were using the clip to demonstrate that inserting a feeding tube wasn't that bad. The use of force on an unwilling participant is the difference. It is very different being held down while a tube is shoved into your head unwillingly than it is to calmly set yourself up for something you need to do.
The context of choosing to die in this method is very different than being forced into it. The man himself said he will be struggling. He will die panicked and afraid. I'm sure this method is perfectly fine when someone chooses euthanasia. I can't assume someone who is being forced into it is going to have a peaceful or painless death.