I don't think so.. there is only one place this constructor is called from I think in CDistributedFileDirectory::getFile(, which can deserialize a file descriptor from a foreign Dali, in that case only does it create a unattached IDistributedFile with associated user.
In all other cases, a new IDistributedFile has no user, until it is attaced (with attach()), at which point a IUserDescriptor is passed to attach.