There is a continuing bug that, when printing, that invisible layers will be included. Until that bug is fixed, having a password lock may not be the best way to proceed.
The workaround is to delete the Layers with proprietary information from the file that is provided to your collaborators.
It's easy to take the returned file, Select by Layer and copy back into the original (after deleting the same Layer name from the original).
TC Pro Platinum 2017, 2016 & 2015 (all with LightWorks) & V21
System: i7-5820K @ 3.30GHz, ASRock X99 Extreme4, 16GB DDR4-2133 RAM, Gigabyte GTX 970, Samsung NVMe SSD 950 (256GB), Windows 7 Pro (64-bit) SP1