Not so sure. We don't know what the non-cooperation relates to. They can't just ask anything, I think.
Any PL request has to be.... "in exercise of its power of inquiry" into a "suspected breach". And then only from the club, manager, player or official.
They could ask the club to provide information from third parties but they have no right to it. Even when they changed the guidance (in the middle of the investigation, no less) the requirement was only to provide third party information "if able to do so".
So it's difficult to say, I think. I still have in my mind that the non-cooperation relates just to third party information in which case the club has more of an argument against the allegation. But I accept I am probably the only one that thinks that, so I suppose it's more likely the panel will err on the side of the PL for procedural reasons, like CAS did.
A couple of points on CAS. Iirc, they didn't reduce the fine to 10 million for non-cooperation, because UEFA never said what the original fine was for. They imposed what they thought was a reasonable sanction for the offence. And I don't think they mentioned any leaks as a mitigation, did they?
Anyway, could all be bollocks, as always :)