The marking of VFR lanes around controlled airspace is partly avoidance of CTA and provided for safety. This may not necessarily mean that landing areas are afforded at all times, however it does organize traffic into a stream for separation purposes in confined areas, and provide key landmarks for navigation to assist such. There will obviously be times that landing areas are at a premium, that is why I used the word 'mindful' and 'consider'. So that a pilot should be flying to maximize the chance of successful landing following engine failure at any point, but there will be short periods where this may not be possible.
In the case in point the pilot somehow had to choose between a water landing and an extreme maneuver. Why is that? If they had flown a proper circuit to land at the beach, then at any point gentle turns while gliding to point towards land would have sufficed. It sounds to me the pilot was most likely intentionally too low among other things, resulting in no other options.
The fact still stands though that at low altitude you should be trained and rehearsed at just lowering the nose and accepting what is ahead of you with mild turning allowed. The same way steering to avoid obstacles on the road vs maximum braking straight ahead is frowned upon by law. Remember that swerving to avoid something is exactly the same, if you succeed and nobody is hurt and no damage you will drive away feeling like you avoided a bad situation, if you don't and somebody is killed you will have an investigation into why you swerved vs braking, and it will usually point out that if you braked the damage would have been less and most likely avoided a fatality. And since driver training is aimed at braking rather than swerving then you are in a bad situation legally.
That may be the subjective purpose, but that "jury of peers" rather than "specialists" would make the reasonable assumption that 'the powers that be' had, by putting the route on the charts, implicitly endorsed it as a safe option.
The panel of specialists would still have to consider what an average pilot should know and do vs what occurs. I agree that if an engine fails in one of those lanes and you are forced to land on a road, or trees as a result, you will be treated in a much lighter manner than this case. If you were complying with the route and altitudes as specified and you attempted to maneuver in a safe manner but could not achieve a 'safe' landing then a jury or panel of specialists would both be empathetic. The question then would be whether your actions led to the engine failure or such.