I think this is a good measure, as it prevents third parties from knowing what my username is if they look over my shoulder.
I have some concern when I use my computer at public locations and worry that some people can look over my shoulder to see I am using the forum, have an account here and its username. It's pure privacy concern and if theymos can approve this patch, I will appreciate it a lot.
The way I'm thinking of approaching this is to move the little +/- icon up one row (next to the SMF logo), and then making it so that when the header is collapsed, it'll look like this:

I like the first one because sometimes I need to read news on important updates from the forum and sometimes I need to use search.
Thank you doing the patch and going further by listening to community suggestion, it's long waiting time to get opinion of theymos / Cyrus, approve it or dismiss it.