because I have read at least 3/4 of his many books and there are many many examples of stories where a boy is the main character and/or where a boy and man have a close deep relationship.

These are the ones I have read from a list I found online that star a young child or a teenager some of them have a deep bond with a non family member. Some are girls but the majority of these are boys which is why I say he is a BL.

Carrie
Salem's Lot
The Shining
The Stand
Firestarter
Cujo
The Darktower I: The Gunslinger
Christine
Pet Cemetery
Cycle of the Werewolf
The Talisman
IT
Eyes of the Dragon
The Darktower II: Drawing of the Three
Tommyknockers
My Pretty Pony
Four Past Midnight
Needful Things
The Darktower III: The Wasteland
Desperation
The Darktwoer IV: Wizard and Glass
The Girl Who Loved Tom Gordon
Hearts in Atlantis
Dreamcatcher
The Darktower V: The Wolves of Calla
The Darktower VI: Song of Sussanah
The Darktower VII: The Darktower
Cell
The Long Walk
The Body (aka movie Stand by Me)
The Regulators
Children of the Corn
The Langoliers
The Lawnmower Man
The Mist
Popsy
The Raft
Suffer the Little Children
The Library Policeman

I have not read any of his newer ones since the last Darktower book came out and even before that I have not read every single one.

Obviously I am aware that an author does not equal his works but if more than 3/4 of a prolific author's works are on one topic than it does make a good case.