Well it won't handle just any extremity. Too drastic change in elevation for one. Basically, the solution there will be that it won't allow you to create roads that go over these limits - it will highlight the segments that need to be corrected.
Besides, nothing would be able to climb that curve anyway
When doing serpentine curves, the turn must be on the same level, you need to get the lower road to the elevation where the turn will be, do the turn on that level, and then continue up from there. The default way point placement won't help you here, as it places the points on the ground level there, and so it leads many people to this design, but they'll soon find their mistake when trying to drive over it.
I apologize if you knew all that and just wanted to show the issue
Hmm, maybe the road builder could perform some adjustment here automatically. For example, when it finds out the way point was laid down on a slope and curving, it could adjust he elevation.