I think there is a problem with the statement that vegans don't heal. There are many factors that deal with healing, some of them genetic.
I have a very rare genetic condition that causes me to heal at a much higher rate than normal. It, also, dampens down the pain when I am injured. They discovered it when I started donating platelets back in the 1990's. One of those 1 in 100,000 lucky breaks. It, also, has an unfortunate side effect that may cause me to have a higher risk of heart attacks or stroke.
I was officially designated by several orthopedists as a "medical miracle" after a serious fall 4 years ago. I fell and broke my shoulder in 4 places, 20+ fractures, the ball that fits in the joint split into two pieces, bone pieces were "floating" in muscle, and my shoulder was dislocated. I drove myself to the ER, and an orthopedist referred to my shoulder as "completely destroyed", and offered me top of the line opioids for the pain. Looked a little startled when I said it didn't hurt as long as I didn't move it.
I saw another orthopedist 3 days later, who referred to my shoulder as " completely shattered", and told me that he wanted to schedule me for immediate shoulder replacement. He looked a little bug eyed when I told him that I would take the disability "as long as it didn't hurt".
4 weeks later the orthopedist said my shoulder was completely healed, and was stronger than before. Still no pain. I had already regained about 70% of the mobility in my shoulder. I went into physical therapy for 6 weeks, and regained 85-90% of the use of my shoulder. The only thing I can't do is fully put my arm behind my back. It didn't even hurt when I was in physical therapy.
I'm 43 years vegan, and my healing abilities have nothing to do with being vegan. As Lady Gaga said, "I was born this way".