Well, Amanda did not mention the name of Rudy to the police before her arrest, that is sure, because the police learnt of Rudy from Bonassi (the plantation master downstairs)
And after her arrest she availed herself of the right to silence.
When do you think she spoke about Rudy to the police?
From the Micheli Report we get:
BS had been heard three times during the preliminary investigation, between 2 and 4 November: only the third occasion, as already mentioned, had reported that his house (downstairs at Via della Pergola 7, which he shared with the villagers, S., and M. L.) was frequented by a guy nicknamed "the Baron" of South African origin, recalling that he was in the apartment with his friends one evening when the test was returned. B. claimed to have noticed that the "Baron" was very drunk, so that soon after he had slept on the toilet: he had added that the boy in question "had a physical attraction for A..
No mention of "Rudy" there.
But in the next paragraph:
Testified in the hearing, the witness recalled that he had already glimpsed the G. at the basketball court, first recounted the episode, then position it in the house the evening of the presence of R. about a week before the murder, stating that occasion - unless I'm mistaken - there were also A., M., M. and the previously reported C. (Later in the narrative, but reference B. GS). However, correcting the earlier version at the point where he reported having found the group back into the house but in reality he was sleeping and was awakened by the noise of their return from the other, then looked out the living room.
Now he is talking about G (presumably Guede). When is this hearing? The context shift and the details sought about G indicates it is not a continuation from the 4th.
A few paragraphs later we get:
B., formerly called in by PG on 11 December 2007, ie a few days after the return of G. from Germany, claimed to know the G. some years, avendoci often played basketball. On that occasion, however, stated he had never shared the way we do, to be R. a habitual liar accustomed to consume alcohol and drugs, and to annoy the girls harassed in public and trying to kiss them.
Is this a new hearing or more details from the last? It's been several days since Rudy had been identified so it is possible that Stefano had also been called in for a hearing before the 11th.
Amanda did not speak of "Rudy" before his arrest because as she said in her testimony, she did not know his name. She had however spoken to the police several times about the boys that visited. He she mentioned the party downstairs? It's possible since these were boys that met Meredith but we don't know because we don't have those early police statements.