So, I have a coworker who started recently in the last year at my office. They have prior experience in the field and are proficient. My boss gave them a task several months in to them working here and for about a week whenever they were asked what they were doing they said they were working on that task. This sort of task usually doesn't take that long.

The next week my boss looks at the file they were working on and there almost nothing there. They ask me what I knew and I told them I had heard them say they were working on it basically all week and maybe they had it saved locally on their computer. When they got back the next day they said they still needed to finish and it took them another couple days to finish.

It wasn't a training issue. The task wasn't hard just monotonous and I had previously worked with them on a similar thing and they even taught me some tricks I didn't know which help speed things up.

Because of this though my boss told me they wanted to fire them. After talking to me they decided to not go though with it.[They are training me to be the next manager.]

Should i have told me coworker how close they came to being fired?