I am sure that in the past most of us would not know what grade the copper was. We now have more information about the grades which has to be a good thing. I have never heard of a model steam locomotive causing bodily harm, and long may that continue.
As the paragraph states it not how we heat it, eg electric weld, it's the temperature and the grade that can be at fault.
I am sure that the little pink person in your photo will ride your machine and her and others protection by using proven methods and correct products will ensure their safety. After all we are using standards produced after the incident in the 70'80's where a refinery blow up, after which the pressure systems regulations were introduced.
Bri