In reality this project does indeed implement a functioning custom JS Engine, Layout engine, painting etc. It does borrow the CSS selectors package from Servo but that’s about it.
Plus that linked comment doesn't even say it's "nothing more than a non-functional wrapper for Servo". It disputes the "from scratch" claim.
Most people aren't interested in a nuanced take though. Someone said something plausible sounding and was voted to top by other people? Good enough for me, have another vote. Then twist and exaggerate a little and post it to another comment section. Get more votes. Rinse and repeat.