Well, the energy levels used in those devices should be miniscule, and the wavelengths used are well studies. The problem with x-rays - was lack of studies on health effects, and regulations on those effects. I think, since that time, we've studies radiation (be it light, rf or other parts of spectrum) much more. There is indeed a possibility that we're overlooking some bio-electromagnetic interaction effects; for instance now there is some evidence that led lights might not be harmless - but again, it's not the they affect biological structures somehow, but the lack of spectral components has some effects. It is an interesting topic to research. But, the lidar "should" be safe