It isn't exempt from anything; the majority opinion says "The Act’s statute of limitations establishes a three year period for filing suit, which begins to run

It isn't exempt from anything; the majority opinion says "The Act’s statute of limitations establishes a three year period for filing suit, which begins to run when a claim accrues." The question is when the claim accrues. As in your example of CSA cases, they decided it's from when the victim discovers the crime and not when the crime occurred.