Maybe you're getting confused because of the protections provided under most good sam laws to medical professionals vs laypersons. When medical professionals render aid in an emergency, they are expected to provide a level of care consistent with their training and expertise. In contrast, laypersons are typically only expected to provide care that a reasonable person without specialized training would provide under similar circumstances.I am not looking to pick a fight here, but where are you pulling these assertions out of?
Dispensing of medication is not generally considered first aid. Oxygen is and because of specific first aid certifications have been developed to address, and now we are seeing Narcan. But even the difference between EMT's and paramedics you see medications as being a big issue. ABO is USP data sheet ABO
As for the SDS the significant bit there is "Other Means of Identification," the link you provided is the generic SDS for Oxygen on airgas's website. You get that same SDS regardless of if you click on it from USP Medical, Industrial O2, or ABO.
If you look at some cylinders, you'll see that medical O2 is labeled oxygen, compressed usp and ABO is labeled oxygen compressed "Aviator's breathing"
Regardless the pedantics around ABO vs USP is offtopic.