The result shows that an increase in the debt-to-GDP ratio of 1% leads to an increase of the real rate of interest on bonds os 0.07%. In other words, the effect is in economic terms insignificant. Much ado about nothing.
PS: As Nate Cline and Franklin Serrano kindly noticed, causality most likely runs from the rate of interest to debt. Sure thing; the point here is just to note that even if the conservative point was correct, the actual effect would be insignificant.