Your summary is stronger than the conclusion of that paper. They also didn't compare stainless steel to copper, they only established copper should work. Here is a random paper I found (first when searching), https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7123372/ which gives the lifespan of MRSA on copper at 6 hours, and on stainless steel at 72 hours - the important take away here is the lifespan on both is far too long so rely on surfaces and so we must disinfect surfaces not relying on their ability to kill bacteria. We also need to get health care professionals to wash their hands more - the article quotes some seriously awful handwashing rates.

Note that the above paper only quotes lifespans for a couple microbes. We care about all microbes, if even one harmful microb of any type survives we have an infection vector anyway.