This guys encounter has changed. As you kill him there are three waves of desert flora/fauna that help him. Each wave has 5 mobs. One is scorpions, One is of cacti, and I do not remember what the other one was (maybe snakes).
The rest of the event is still true about having to kill all the desert giants before he becomes targetable. This means not only the ones at the tents but ALL the desert giants which are the ones behind the rocks and the named ones.
Soloed him with a 90 mage with no difficulty.

Earring of the Stormcloud
Enameled Giant's Finger Ring
Falchion of Storms
Idol of the Tempest Storm
Writ of Karana