Actually, it wouldn't:
1) The accusations were indeed published.
2) The plaintiffs, a.k.a. the Police Officers, are readily identifiable as the Officers on duty at the station the night Knox was questioned.
3) The remarks are defamatory towards the reputations of the Officers
4) The published information is false
5) and the Parents made the claims
Now, as for whether the malice and/or reckless disregard for truth can be shown, well, that remains to be seen. I'd have to do a bit more research, but I'd be willing to bet that the Defendants in this case made the accusations after the truth had become clear (that the statements made by Amanda were indeed false), that Amanda had been charged with libel for the same statements, and that the Italian Justice System (whether the Courts or Police Dept) had requested that the parents cease their defamatory remarks. Realistically, though, I'm not going to bother with the research. I'll just wait for the case to be tried and see what is presented by both sides.
While I do understand the argument that the parents shouldn't necessarily be accused of libel/defamatory speech when/if quoting their daughter - there's a point where the parents are making the accusations themselves and hiding behind "well, she said it first". IANAL, but IMO, that is not a sufficient defense.
My dog in this thread is merely to point out the lack of critical thinking that has jumped up here on the first page. No one here has read the indictment, and yet everyone's certain that it's just the Italian Courts trying to pressure the Knox/Mellas' through a lawsuit.
We don't have to read the indictment to know that this (like most of Mignini's prosecutions related to this case, and there have been a few!) is malicious. You say that the truth has become clear, and that Amanda's statements about what happened in that room 'were indeed false'. None of that is true.
Mignini claimed after an 'investigation' into the claims, that there was 'no proof' (u-r-l: seattlepi.com/local/420882_knox30.html?source=mypi) to support the allegations. But how was Amanda supposed to prove the truth of her claims?
How are the Knox's supposed to prove the truth of these claims?
1) The interrogation was not recorded because apparently Amanda was only a witness when the interrogations of 5th / 6th Nov took place.
This claim that Amanda was only a witness is most likely false as a statement was made on the morning of 6th by the police, to the effect that Amanda had 'buckled' and confirmed facts 'they already knew to be correct'. Therefore, Amanda was indeed suspected of the crime BEFORE the interrogations, making the lack of recording and the police's response to Amanda's request for legal counsel borderline illegal.
(Question- was it because of these facts that the statements resulting from these interrogations were 'disallowed' by the court? - If it weren't for the Kerchers' lawyer Maresca using the 'alongside' civil suit to sneak them in before the jury)
2) Police accounts of the interrogation are inconsistent and patchy (one police officer, not in the room, reports Amanda 'screaming', another fails to note the existence of the first interrogation in her notes, etc etc).
3) Patrick Lumumba's treatment by these same police at least bolsters Amanda's claims (u-r-l- dailymail.co.uk/news/article-496218/I-fired-Foxy-Knoxy-hitting-customers-Patrick-Lumumba-reveals-framed-Merediths-murder.html). They at least support the claim that this kind of treatment is part of the police culture in Umbria / Italy generally.
There you go, three prima facie good reasons for thinking that the Knox's claims might be true.

Just because you think the content of Amanda's statements are false (which I agree with) it doesn't mean her statements relating to how the interrogation took place are false.