I believe this is a common tactic.

The point is to do the difficult and dangerous parts in bright daylight, especially with sunlight shining *down*. That's usually the parts near the summit, both before and after. Since you want a margin for error you start on a track to arrive well before noon local time. Under no circumstances do you plan to get to the summit at noon: you'll have no dwell time, no rest before the descent and less margin for error.

The first and last parts of the climb are usually not risky or arduous, so it's not a major issue to do them by flashlight. The idea is to plan everything around the most difficult parts and to make sure those parts are done under best possible conditions.

If conditions at lower elevations don't permit a nighttime hike then that means a multi-day expedition - the schedule at high elevations is not shifted to accommodate such.

PS. If their intent was to watch sunrise from the peak that's a different matter.