Hmm, I must have missed that. I stand corrected, then. Perhaps the author thinks copyleft can be divorced from open source? They didn't claim to be open source here, but they do claim to be (very strong?) copyleft -- almost like a single-source copyleft kind of interpretation. But yeah, I get it now. ty

As others have pointed out, it's very likely the "author" was an LLM. It's clear no lawyer ever gave this a once-over. I can easily imagine a manager telling ChatGPT "write a copyleft license that doesn't allow other people making modified versions of my software".