They don't just instantly depressurize the plane to 8,000 feet, that's just the highest cabin altitude that is typically set, as going higher than that can lead to hypoxia problems, and lower can create too much stress on the airframe. So pretty much as soon as you start ascending, the pressure differential is going to be high enough you're going to struggle to open it, if you could get it to budge at all.
The lack of specific citations on a lot of these is really calling the whole image into question. If you can't specifically point to a page in the source, it shouldn't be included. It just makes it easy to obfuscate the real issue.
As another lifelong beneficiary of white privilege, thank you for pointing this out. I never considered this perspective.