There is a huge difference between health and safety thinking and the use of skills. Again this accident would not have occurred if the hazard assessment and risk analysis was done that indicated that felling a tree close to a worker could result in death. This thinking needs to be done first...
Well your British Mycology friend will have a species by the same name but it seems clear that the British and North American Laetiporus sulphureus are not the same species. Maybe Kevin Smith knows if somebody is working on this problem at the moment and will revise the genus.
I wish I could see the underside to for look for gills, teeth, pores, maze etc.
If it is sulfur shelf the colour has faded since August/September when it would have been at peak