Oh no... You absolutely can't be doing maintenance on an escalator while people are walking on it. Not only unsafe, that's just not going to work at all most of the time. The maintenance crew and the public would be in each other's way.
On the other hand, when it breaks on a Monday, and the crew says they can be there to do the repair on Thursday, that means that it's safe to use the escalator as stairs for a couple of days while you wait.