Answer

No, it is not necessary to authenticate for Twitter search.

Example

ruleset a60x155 {
  meta {
    name "Twitter search"
    author "Mike Grace"
    description <<
      example for devex            
    >>
    logging on    
  }
  dispatch {
    domain "example.com"
  }
  global {
    datasource twitter_search <- "http://search.twitter.com/search.json";    
  }
  rule newrule is active {
    select using ".*" setting ()
    pre {
      json = datasource:twitter_search("?q=kynetx");
      results = json.pick("$..results");
      text = json.pick("$..text");
      first = text[0];
    }
    notify("Twitter Search for Kynetx", first) with sticky = true;
  }
}

Example Result