Where's the "Protection" in TIPS?

``It is ironic, then, that the only true investment to ever bake in a negative return after inflation is Treasury Inflation Protected Securities—ironic because the very purpose of TIPS existence, of course, is to provide for a guaranteed real return. In fact, TIPS recently yielded a negative return for the first time since their inception in 1997. The 5-year TIPS note ended February 29th at a -.043% and remained negative through most of the month of March.''