If the lock manufacturer asserts or implies greater protection than the product offers (which is actually quite common), then yes, it's a scam.
I encourage you to read their whitepaper, where they state that world id is indeed a proof of personhood. The allegation in this thread is that it fails at proving that someone is a unique person, and it cannot possibly due so because of the oracle problem. Therefore it is a scam.
"proof of personhood" is something of a term of art which worldcoin did not invent. They are not literally claiming they can prove, in a mathematical sense, personhood. What would that even mean? See for example this, which seems to have originated the term in 2017: https://berkeley-defi.github.io/assets/material/Proof%20of%2...
"proof of personhood" was created in contrast to "proof of work" and "proof of stake". If you want to get technical "proof of work" is also not a mathematical proof, it is more of an argument of work, since it's possible to get lucky and find a low hash without doing all the work. The word "proof" is not doing what you think it is doing.
There are a couple other "proof of personhood" protocols and none of them mathematically prove personhood, because that is obviously impossible, some of them are listed at the beginning of this post: https://vitalik.eth.limo/general/2023/07/24/biometric.html
Separately, I strongly suspect that your idea of worldcoin's "stated purpose" is not something they have ever stated.