RR are flailing in an attempt to slither out of their current predicament.
But unfortunately, they have to deal with facts that are now publicly available. Relying on their reputations and verbal sleight of hand will not save the day.
I think five points should be fairly obvious to all :
i) RR made a huge mistake. This isn't about one figure. It is about numbers at the heart of their argument.
ii)There is nothing magical about 90 or any other number.
iii) There work does not speak to the most important issue facing policy makers today - how much will an increase in debt affect economic growth ? This is because they have done nothing (absolutely nothing worth mentioning) to separate effects of growth on debt accumulation and effects of debt accumulation on growth.
iv) The quality of their analysis barely meets basic senior undergraduate levels. The techniques used are really pathetic. Why not use basic graduate level panel data techniques (fixed effects, robust standard errors, clustering etc.)
v)RR are incapable of providing a decent apology without coming across as both condescending and slippery.
I don't understand why their work wasn't questioned and studied by unbiased economists and a rigorous statistical and theoretical/quantitative analysis was not done. It is surprising that this was left to a Socialist/Marxist department to point out the many errors.