If you have some evidence that this is the case, feel free to give it. But they've already outsourced the running of the registry to somebody else, so any obvious efficiency gains have presumably already been taken. And if they haven't, there's no reason to think a fresh-minted PE company would do any better than hiring a competent manager.
1. Earn less than IS would
2. Charge more than IS would
It's actually:
1. They could earn less than IS would, because they're generous, incompetent, or some other reason
2. They could earn more than IS would, because they increase the prices, run PIR more efficiently than IS would, increase the number of registrations more than IS would, or some other reason
In scenario two, which is the most interesting, they could jack up prices, but they could also run the business better, such as running the business more efficiently or driving more business through advertising. I agree with you that the former is likelier, but not necessarily the only reason why the deal would have a positive expected value for Ethos. It could be that the deal is a win-win one, where IS gets more money than they'd be able to make out of PIR, and yet, Ethos comes ahead too by running it better than IS could.