Not based on the research you have posted can you come to such an emphatic conclusion.
But isn't a polytrack exactly the same as a Tapeta i.e. a surface made from a mixture of silica sand, wax and artificial fibres.
Tapeta: a Thoroughbred Racing and Training surface comprised of a carefully selected mixture of the finest silica sand, wax and fibres that have been extensively researched and simulate the root structure of turf.
Martin Collins Polytrack: A mixture of silica sand, recycled synthetic fibers (carpet & spandex) and recycled rubber/pvc. In cold climates, the mixture may also include jelly cable (plastic insulation from copper phone wire). The entire mixture is coated with wax.
What's the difference?
I don't believe the evidence you produced is conclusive. I also haven't seen any evidence or properly structured research to prove one way or another.
The research that has been quoted from what I can see is an analysis of the data contained in the North American Equine Injury Database (EID).
Canadian authorities have also claimed that the improvement in fatality statistics is related to changes in withholding times.
Do you consider the Flemington or Moone Valley Strathayr courses Turf or artificial?