1) If most Americans haven't reflected that law and legislation are different words then so be it, but I don't intend to hold myself accountable.
2) Bear in mind how the "they're obviously going to be scanning internet traffic" conversations went back in the 90s and 00s (where it went from absurd tinfoil hat talk to common sense assumption basically overnight). If they do turn out to have secret legislation that feeds into the FISA court then I reserve the option of being smug in retrospect. It seems quite reasonable that they would need secret legislation to operate the secret court that produces secret laws likely enforced by secret police. There is pressure to recreate the whole legal system with the word "secret" in front of it to make any individual secret part work.
It's a secret court; I doubt any of us know what is going on in there. This is one of the major problems with secret courts, it is not possible to opine on how they are working without speculation.
It’s not that they’re different words. It’s that the word “law” has multiple distinct meanings. One (the more common meaning) is a synonym for “statute.” That’s not what’s discussed here.
Your second paragraph is actually exemplifying the exact type of misunderstanding of the situation that I was alluding to. You really don’t need secret legislation, or even secret statutes, or even secret rules to produce the “secret law” referred to in the article. All you need is secret decisions.