You have no evidence for that at all it's just your bias talking. You have no idea that the role Cummins is playing is substantially different from previous advisors or if it would have differed from Milne under Corbyn. It would almost certainly have been worse seeing as Corbyn is clearly not a bright bloke- his ex wife saying he had never read a book etc. He's also clearly quite a passive man, certainly compared to Boris who may have his faults but is hardly a shrinking violet.