I don't think that 1S is having problems whit fake files but that may come when 1S gets popular.
The idea is that nobody is going to add a friend how is searing fake content BUT if this person joins a community then he can infect the network whit fake content, to prevent that you can add an option to prevent the search term from being passed onto a 'community server friend'. (if its technically possible)
I assume that a 'community server friend' can return string searches that is, else there isn't a problem.