It would imply that she was called in front of a grand jury to testify against Aaron Swartz. I presume she initially refused to do so on the grounds that it might incriminate her - as is her right under the Fifth Amendment. Therefore the government gave her a letter of immunity, something they can do without her permission. Once she was immune to prosecution, the government could compel her testimony.

I assume she didn't want to go to jail (she does have a daughter, after all), so she testified. I can't say I'd hold that against her. You have very little rights in front of a grand jury.