What a crazy discussion.
What about someone totally losing situational awareness, doesn't take care of wind, not recording waypoint overflights, not checking fuel to destination and then: MISSING Top Of Descent of your very own FMS and flying beyond the last waypoint on heading or what, overhearing the chime.
Don't make the public believe that you cannot fly without ATC, there are lost comm procedures that are supposed to be followed. You simply don't let your plane fly on heading to somewhere.
No, there is something definitely wrong here, not just dialling in a wrong frequency, by the way without a word of acknowledgement when leaving the old one...
That ATC didn't remember which frequency it sent the aircraft to and on which it was last heard is another scandal. And no clue about lost comm procedures...