The only suggestion that anyone has “gone back on” anything comes from your post, not the information from the source.
I find it concerning that you are resorting to assumptions and inventions to justify government overreach.
If you grant the State the power to arrest you, the victim, to be sure you testify, one day, the State will reason that it also has the opposite power—the power to arrest you to ensure that you do *not* testify.
I am simply speaking generally from my experience, because I'm pretty sure there is a lot more to this story that is not being told.
Incidentally, the idea that a corrupt government would jug you to keep your testimony out of court forms the central theme of R.L. Stevenson's Catriona or David Balfour (same book, different titles in England and America). It's the sequel to Kidnapped, which is pure action adventure, but it's a political thriller with some adventure thrown in. A really good read.