Earlier quoted context omitted.
not if you have a server that handles the search box and is CSRF save. And if it isn't csrf save you don't need the timing attack since you already have the content or not.
This is incorrect. As I believe the author notes, Same Origin Policy prevents you accessing the results of endpoints you can CSRF with at least one exception (JSONP). The author uses the timing of the forged response to determine if the value was cached. Again, the attacker cannot access any information from a cross-site forged request in this case other than timing data.
User Input -> (CSRF / Auth) from Your Server -> Your Server -> Lucene
Most implementations will do it like that since everything else is unsafe by design, so the article is pointless.