Tbf to the PL, they had a difficult decision to take. Assuming the club has withheld third party evidence that would irrefutably prove its case (which I strongly believe), the PL had a list of allegations without sufficient evidence from the club to counter them. I am talking the sort of evidence that the club provided to CAS (to third party statements, financial information from third parties and the like).
What should the PL do? They couldn't really use the evidence presented at CAS because they hadn't seen it themselves, just read about it in the CAS award. I am not so sure they could do anything else at that time, but refer the allegations that hadn't been sufficiently countered to the IP. As I have said a few times, I think the club has played it all well, legally speaking, forcing the PL to shit or get off the can, knowing if they shit out 115 allegations, the club has the irrefutable third party evidence to counter them.
The time when the PL could have changed tack was during the investigation, but after the CAS award. They could have accepted that verdict, on Etihad for example, and the explanation given for Etisalat, and just investigated the others that were new or time limited at CAS (to the extent they aren't also time limited here). But they didn't, so here we are.