This is objectively true, so the downvotes are a bit baffling. Credit ratings are directly related to the rate premium bond holders demand for the extra credit risk. It is simply a fact that if the credit ratings are lowered to a sufficient extent, the rate that investors demand for the borrowing will make it no longer feasible.

About 10% of HN downvotes I see are applied on ideological rather than rational or grounds (leaving out those for rudeness or other inappropriate behavior). I take an irrational downvote as a small victory, albeit after making sure that it wasn't just for being a smartass or missing the point.