Here's an article about the rule being made in the first place (IIRC, the rule got made at the same time Windows on ARM was itself first given to manufacturers): https://softwarefreedom.org/blog/2012/jan/12/microsoft-confi...

I'm not sure how it's working on those laptops, but I'd imagine the choices are either that Lenovo got given an exception, the rule as a whole got changed, or that Microsoft just hasn't noticed or is intentionally looking the other way.