Trading TVIX is complicated. I don't understand it myself. But what I do know is that TVIX is a pos for longs because it suffers from a negative roll yield. It tracks the two front months of VIX futures. Because the futures are trading at premiums, it suffers from a negative roll yield. In short, you're losing money from this negative roll yield if long. TVIX is best for daytrades or short term trades. Not good for longer term trades unless everything aligns just right like last August.

The article basically points out that TVIX was trading at a high premium compared to its NAV. The article was written 10 days ago. Since then, the premium has inflated exponentially more, so it was even more dangerous to be long TVIX. Longs could see this premium yanked out from under them like today. His point was that it was risky to hold TVIX long at the time because it was trading at 9% premium to its NAV.