That person just claimed it works. It does not. The implementation would have to treat exclude like an array and loop through it's elements. It does not, as you cannot even do a single element exclusion with []=.
Also, that exclude thing does not seem to work, if not logged in. Would explain the complains I see sometimes, that it does not work. Single tag exclusion does work. But not in search. Search does not even limit itself to games or assets, you cannot specify what to search. That might change in the future, as the whole search system will get an overhaul. Maybe they even implement official tag exclusion, maybe even multiple tag exclusion.