Yes, Lorentz transformations prserve distances, they describe the isometries of the hyperbolic plane.
As discussed in the question you referenced, the distance between two points $u$ and $v$ depends on the bilinear form $B(u,v)$ which can be written as
$$B(u,v)=u^T\,\eta\,v \qquad\text{with}\quad \eta=\begin{pmatrix}1&0&0\\\0&-1&0\\\0&0&-1\end{pmatrix}$$
Now a Lorentz transformation is _defined_ as a transformation which does not alter the bilinear form. A Matrix $\Lambda$ is a Lorentz transformation if $\Lambda^T\,\eta\,\Lambda=\eta$. Which means $B(\Lambda u,\Lambda v)=B(u,v)$ and therefore the distance of the transformed points has to equal the distance of the original points.