The Guinea International was one of four players ostracized by Mourinho after last week’s shock 6-1 defeat to Bodo/Glimt in the Europa Conference League.
After the game, Mourinho claimed his fringe players were inadequate and “he only has 13 players” in his squad who are good enough.
He then dropped Diawara, Borja Mayoral, Gonzalo Villar and Bryan Reynolds from his squad entirely for the Serie A fixture against Napoli on Sunday.
They have not been picked for Wednesday night’s trip to Cagliari either.
“I don’t understand the message he’s trying to get across.
“Is Diawara being made a scapegoat? Is he being made to pay a heavy price for an error? Or is an attempt to force the club into acting in the transfer market?
“If it is for these reasons, rather than just poor fitness, or he feels the player is unable to understand the tactical requirements of the coach, then I think Mourinho is creating an uncomfortable situation.
“It is inexplicable but Diawara will adapt. Amadou is an exceptional professional,” Piraino told Tuttomercatoweb.
Diawara, 24, has only played seven minutes in Serie A this season.