I was in need to disable the CollapsibleVector feature for anonymous users. I've played with the two configuration options mentioned in the extension's page with no success in order to accomplish this task. Finally I decided to add a third option that can be controlled via
$wgCollapsibleVectorFeatures['collapsiblenav']['anonymous'] = false;
Here is the patch, and the relevant instructions: https://gist.github.com/pa4080/0e7770dfb497f6ed543c8be8110c0b66
I think it is useful option and probably it could be added in the next release of the extension.