People who understand the Constitution know that these federal judges, appointed under Article III of the constitution, cannot be fired.
It might also help to note that the FISC judges have day jobs as ordinary District Court judges, and the judge who wrote the letter is a judge for the District of DC. There is no standalone FISA court with dedicated judges who do nothing but FISC work.
It would also help to note that most of what the FISC does is grant warrants. In the normal, non-FISA context, warrants are granted under ex-parte proceedings with only the government being represented. There is no public advocate, and warrant hearings are not adversarial in nature. Almost all normal warrants are also approved, making normal courts rubber-stamps in the warrant context.
This isn’t to say there aren’t problems in the system, but it is ridiculously disingenuous to present the issue the way Masnick has.