Keshia Knight Pulliam -- Radio Silent with Bill Cosby for Years

Bill Cosby was the elephant in the room for the season premiere of "Celebrity Apprentice" ... where Keshia Knight Pulliam revealed she has had virtually no contact with the comedian for 5 years.

The episode was filmed way before the latest round of allegations surfaced against Cosby, but years after a female employee at Temple University sued him for sexual assault.

Cosby became the focus of the episode because Pulliam refused to hit him up for a donation as part of the show's challenge. Pulliam was called on the carpet by Donald Trump for not making the call.

Pulliam explained her decision not to reach out to her TV dad ... saying she hadn't spoken to him in years.

But she tweeted Monday, insinuating the silence between them has nothing to do with sexual assault allegations, saying, "That's just not the man I know, so I can't speak to it."

In the end, Trump fired her.