"Product Performance Claims" is simply a way of categorsing what specification and approval claims are made for this oil. In this context, "claim" means statement of conformity rather than self-judged belief.
Your engine needs WSS-M2C946-B1, this oil meets WSS-M2C946-B1 - it's a perfect match.
I think the rub here might be in a subtle difference between US English and UK English...if you look at M1 5W30's PDS, it says "meets or exceed the requirements of" WSS-M2C946-B1 along with some others, which sounds solid to me. The word claim is often used in a somewhat negative context here, like "Steve claims he's the strongest man in the world!"...something that can easily be refuted if anybody bothered to look into it. I think it might not have such a connotation in UK English.
The thing to watch out for is an oil maker saying their product is "recommended for" applications requiring a certain standard, that's a sure sign that they haven't actually gone through the work to get a license.