In a series of tweets posted on Wednesday, Macdonald suggested that Murphy was approached to portray Cosby during the "Celebrity Jeopardy" sketch.
"He knew the laughs would bring the house down. Eddie Murphy knows what will work on SNL better than anyone," he wrote. "Eddie Murphy, I realize, is not like the rest of us. Eddie does not need the laughs."
Current SNL cast member Kenan Thompson ended up doing the impersonation instead.