Before revision:  Then, we show how their reduction from Planar 3-SAT (as well as our adaptation for rectilinear terrains) can actually be made linear (instead of quadratic) .
After revision:  Then, we show how to obtain an improved ETH lower bound of 2^{\Omega(n^{1/3 reduction from Planar 3-SAT (as well as our adaptation for rectilinear terrains) can actually be made linear (instead of quadratic) .