A) Bondholders demanded a premium on interest due to the risk of default.
B) PR defaulted; by implicit contract (the higher rate demanded) which priced in the risk inherit in the bonds, the bondholders are entitled to exactly nothing.
Since bondholders are getting US taxpayer money (a party which had nothing to do with the contract between bondholders and the territory of Puerto Rico), I am far more enraged over the complicit embezzlement of public funds to give to private parties.
That the embezzlement comes with a effective ‘take it or leave it’ style clause that says you can't sue over it - well, tough cookies. My suggestion is take your stolen money and run, as I'd far prefer that they get tar and feathers for their theft.