We have discussed this for sure, especially given how well it worked for Nex AOD. The Sanctum team are keen to do it, but it's very unlikely we can do anything to hide the log for launch.
We ended up suggesting it quite late in development when we suggested a less detailed pre-launch reveal, and it's just not something that is likely to fit into the remaining timeline of development. It's not quite as simple as I had hoped when we suggested it.
If we can't for Sanctum (which is what you should expect), it's still something we'll likely make happen for future bosses / logs that would benefit from being hidden day one.