Earlier quoted context omitted.
That makes it an effective form of communication, but not correct. If I talk to someone who's not computer-savvy and they describe a workflow as "I put the USB in the CPU and then drag all my files onto my screen" (verbatim quote) I can figure out what they mean and work with them, but they clearly don't understand the concepts.
Your comment contradicts current linguistics. There is no "correct" separate from usefulness in communication. If someone wants to write a REST RFC, and people can talk about "RFC-6789 Compliant REST API" then correctness would reenter the picture.
I think you may have misunderstood your source. Subjective truth is only half of the equation. The other half is testing rational models against experience. If you understand the constraints of REST, you understand that it has implications not met by the API in question and thus claims to be something which it clearly is not.
Just because I tell you I'm a duck doesn't mean I'm a duck.