Apple was on the USB Implementers Forum that designed USB-C so.. I would say they could definitely be credited as a co-inventor of USB-C, they also introduced one of the first devices that used USB-C.
That's not what Grubber claimed tho. They claimed solo inventor, which Apple is not.
And then they went too far and introduced laptops that only used USB-C before finally setting at a (so far) happy medium.
In addition to being the sole inventors of lightning (the connector), which directly informed the USB-C spec based on learnings from field use.
Apple doesn't get solo credit for USB-C, but they were certainly essential to it. Just compare the USB-C physical interface to the USB-3 micro or super speed type B ports and compare design sensibilities.