Do you have a source? I just checked the Linustech tip thread and two people claiming to be working for AASP say different than what you just wrote.
"Apple no longer cares if you've caused damage to the device by opening it up, basically we check with you if you caused damage, then remove any modifications you attempted and charge you as much as needed to replace anything damaged. Most stores avoid getting certified for new machines right away as it is time consuming, expensive and usually does not have a very good pay off -- lots of $$ up front, not much $$ generated."
"Hello, I work for a AASP in the United States, and not only do I have the certifications for the iMac Pro but can get parts for these units. The only thing I can think of is that Canada just isn’t there yet with these certifications and parts. I would recommend sending it to a place you trust in the US. I would highly recommend a AASP as it would keep warranty after the repair is done. If it gets fixed with the wrong display or fake display it will void all help Apple can give you."
https://linustechtips.com/main/topic/917597-suggestions-for-our-imac-pro-repair/?page=6