For GC right now, the bond rating is meaningless. It does not change the interest rate (coupon) that they have to pay. It does not change maturity terms or principle. It likely makes no change in the trading price of the bonds either; If the bonds were ever investment grade, then the losses were incurred when they dropped below investment grade. Although rating agencies make distinctions between grades of junk debt, it makes little practical difference.
Rating agencies do not declare companies to be in default; only the bond holder can do that and it requires a trip to court to have contractual obligations enforced. So, the individual narrating knows little about bonds and certainly won't be someone from whom I will take investment advice.
So, if GC is pushed into default, that is not the end of GC. It just means that the bond holders take control of the company and work out the best way to make themselves whole. In fact, there is a strategy to be played in this. Bonds heading toward default often trade at a fraction of the face value. By buying a large number of bonds, if the company works out its troubles, then you make a big capital gain. If not, you can get hold of a viable business at a very reasonable price.