JR specializes in reading biographies with "grains of salt." 
Whatchu talkin' bout, Willis?
I haven't read this particular book, so I can't really comment on it.
However, I will say that authors who write scandalous biographies of dead people, who can no longer dispute their claims, have ruined this "business" for those of us who avoid the sensationalism.
Back in the 1970s, when I was writing non-fiction books about Hollywood, I had no problem garnering interviews with virtually everybody I approached (e.g. Cary Grant, Mervyn Leroy, Mary Pickford, etc.).
Then, a certain author I knew (whose name I won't mention) came out with that piece of crap that claimed Errol Flynn was a Nazi spy, and suddenly the well dried up. People who I'd interviewed on earlier books (e.g. director Gordon Douglas) would no longer give interviews. They no longer trusted
any biographer.
I recall that this aforementioned author used to "authenticate" his claims with statements like:
"So-and-So told me this before he died."Right!
I just hope that, if the information in the Mineo bio is not true, Mr. Sherman and Mr. North sue the author.
That would force him to prove his allegations in a court of law.