Two-Year Treasury Notes vs. CPI Inflation

Grandma said "Never buy a negative yield; and sell, if you should discover you own one" but she never explicated her thinking on reinvestment risk or why she didn't put chocolate chips in the oatmeal cookies. Hmmm.
From Market Oracle:

US government bond yields have now sunk so far, so quickly, that on Thursday this week – in a little-noticed event – they slipped below the latest reading for US inflation.