I doubt many people would buy tickets for a flight with a failing airline. That said, shutting down with effectively zero notice is pretty terrible, and they will probably need to do a bunch of repositioning flights, so they could have kept the lights on for one or two more days.

I agree with this.

I initially meant that they should have finished the flights they already sold tickets for, in some timeframe like one month.

Changed the phrasing so it is more clear.