I think the idea is that the attentive driver will notice the different surface texture and move left.
Likewise, the bicyclist will chose to move right
And it will naturally create a space between the two, without laying curbs.

Had the tiles been laid at a diagonal as shown in the drawings, they would be safe enough to ride on. As it is, it is probably fine for MTBs, but not road bikes.

In other threads, it was suggested that the more isolated bicyclists are, the less visible they are, especially the high speed cyclists. So, if they put in a curb and plant shrubbery between the road and the bike lane, it can be more dangerous. Although, the "Dutch system" apparently forces cars to begin a turn before crossing the bike path, and thus the cyclists are more likely to be visible than if they just pulled up alongside the car.