That’s not a weird request at all, they could have contributed to the USBC protocol before it released, that’s… How it works you know.
You’re asking for proof they contributed before an arbitrary date. Can you provide a list of everyone other than Apple who contributed before 2012?
We can look at the press release announcing USBC from 2013 where Apple isn’t mentioned at all… https://studylib.net/doc/18619173/usb-type-c-press-release-from-2013
It looks like they were mentioned in a 2014 list however https://www.docdroid.net/uf3z/typec-pdf
Those are two completely different lists. One is “the promoter group” and the other is “everyone involved” which are in no way equivalent. It’s like the opening credits on a movie, vs the closing credits. One of the two is inherently going to be more detailed.