Preidler admitted he had his "blood taken out" amid an investigation into a blood-doping ring that brought down five skiers last week.
The 28-year-old Preidler was a member of Pinot's close lieutenant and had been expected to ride alongside the Frenchman in this year's Tour de France.
"It has been very difficult, I even cried because to me it is high treason," Pinot, third in the 2014 Tour and fourth in the 2017 Giro d'Italia, told French sports daily L'Equipe on Tuesday.
Preidler, who admitted to intended doping but said he never actually went through the whole blood transfusion process, joined Groupama-FDJ in 2018, winning a stage in last year's Tour of Poland.
"He was a crucial ally for me. I would like to understand. He had become a friend," added 28-year-old Pinot, who last season won a Monument one-day race, the Tour of Lombardy.
(Reporting by Julien Pretot; Editing by Ken Ferris)
