Not an expert on the LEAP, so this is a best guess...
An engine will restart very quickly following a brief fuel interruption, which I think is what this refers to. It's not documented but it can potentially let the engine recover from a locked-in surge condition or possibly the engine master switch being inadvertently selected off.
In this case switching the engine master back on within 20 seconds will allow very quick recovery (on bigger engines such as the Trent 1000 you get light-off within a second).
May of course be completely wrong so will follow the thread.