His life inspired many films which were either based directly on him (Black Mass with Johnny Depp, e.g.) or fictionalized versions of him (Jack Nicholson in The Departed, e.g.).
Everyone knows the maxim that one should not speak ill of the dead.
You can make an exception in this case.
I lived in Mass. for many years. My favorite Whitey Bulger story is when he won the State Lottery. Everyone knew it was bullshit, but nobody could do anything about it.