Probably because since 1999, these are his managerial terms: -
Juventus 1.8 years
Milan 7.6 years
Chelsea 2,5 years
PSG 1.5 years
Madrid 2.5 years
Bayern 2.5 years
Napoli 1.5 years
So in 7 jobs in the past 20 years, only 1 has been for more than 2.5 years, so Milan is very much the exception...