This might make sense if it is possible.
This (change of default file permissions) should be reported as a bug or feature request upstream too (even if they don’t implement it - we benefit from their comments, perhaps would otherwise miss a good argument to not do this).
You suggested to hide from everyone but root, ok. (Edited)
Related, which was an attempt to hide hardware information even from root:
ticket on virtualbox hardware obfuscation - which was later reverted. The code is still here:
It could be enabled through an optional build parameter which would be easy to add but so far no one has asked for it.
ticket: remove attempts to hide CPU information from VM in VirtualBox
List here: