Wilkinson hasn't featured for club or country since dislocating his kneecap against Gloucester on September 30.
Although he had been expected to return to action over recent weeks, a reaction to certain elements of training has put his latest comeback on hold and led many critics to rule him out of contention for this summer's Lions tour.
"There's no chance of Jonny playing this weekend," said Bates.
"He hasn't trained all week again because certain things are happening with his rehab that are now being very much focused on different areas of that knee.
"That means he can't come and take a full part in training, but if it was a case of us being in the play-offs, say, and we needed him to come and play, he is reasonably close.
"But as it's not absolutely essential, the best thing to do is look after him."