This is one of those convoluted stories you hear when you catch 3, 8 year old boys with a dead cat.
And just like it, it’s total and complete bullsh!t.
If Rosenstein was shopping that nonsense in the cabinet he would be gone within 3 days.
I think Rosenstein has figured out that Trump is going to clean house right after the elections. And that it would be better for Rosenstein and his deep state allies to provoke Trump into firing him now, for reasons like this, than waiting for the housecleaning.