It's obviously conditional on the overall state of economy - if we are in a boring market, the bonds will eventually sell-off. In a flight to quality, all bets are off. That's why if I were doing this trade, I'd do it either by buying puts outright or doing a conditional steepener.
So record VIX sub 10 closes has not been a boring market?

I guess this leads to another old saying, "if you apply enough leverage, no market is boring.