There is a saying in here. Translating these kind of things are hard but I will try with help of google tranlate
"It's easy for a single person to divorce a wife."
If you are professionally doing this, you can not let it go so easy. I think they have to push at Pu side too. We understand ( and Fia also declared that ) from Ferrari investigation that Fia has not got ability to investigate this PU tech sufficiently so need help. If they could not find anything wrong with merc PU that means nothing. And it is a question marq when you didn't find anything with Ferrari but that unfounded thing slowed down Ferrari and it didn't resulted same with mercedes.
( I am expecting at least 10 downvotes