Actually I believe the author either implies that the thing will bust first, or is weighing down the price of its underlying components second (due to excessive inertia in ETF position relative to what would be unfettered price movements in the underlying assets), or third: both.
Bottom line is that if you do not perfom diligent research and want quick and dirty investments for day trading (like ETFs) you deserve to get your dick caught in the meat slicer. No sympathy for you. Chances are TBTF uses the ETF to sit on the miners (disclosure: I’m full in actual junior miner stocks).