He has very high mobility though (especially with Furor enchantment), and effective use of Shrooms can act as escapes. But even then, he has some health from Liandry's Torment and can switch the Nashor's out for a more survivability oriented item and still have 2 AA's per second with Berserker's Greaves.
EDIT: I'm not saying he isn't squishy/killable. I'm saying that he has the option to be a bit tankier without losing a lot of his damage, and can be safer than other APs.