I don't know what they think, but by my understanding Raffaele Sollecito did leave his DNA in the murder room. And I've read the whole Vecchiotti/Conti report.
He did also leave his footprint in blood, by the way.
Four DNA traces of Rudy were found in Meredith's room. One of Raffaele Sollecito. None was found of Amanda, but I am wary about those numbers, because sampling follows a method itself selective. Nobody will know, for example, who was the owner of the long straigth light coloured hair, nor who had grabbed the victim's hir or who covered her mouth: no male DNA could be recovered from those areas. Often you need a Y-haplotype to spot DNA on a victim's body.
On the other hand, I can note that a mixed luminol trace with DNA of Knox and Meredith was found in the alleged burglary (or staging) room, but no trace of Rudy (DNA or fingerprint) was found there where he supposedly climbed in, and searched the room.
Moreover no trace of Rudy was found in the bathroom, where he supposedly must have been to wash himself, while he was dirty with blood and maybe wounded and he supposely touched several things (light interruptor, faucet, bidet); only Knox and Meredith's DNA was found in this bathroom. This bathroom is obviously an extension of the murder scene, since it was a location for the murderer's activity and his interaction with environment.
And, a Knife was found with Amanda's DNA on it which has the victim's DNA on it. I know that you would believe a contamination, but I see no basis for that, in my opinion it is not possible to make this claim even based on the C&V report. I've read the report rather carefully.
A final note: Amanda's false accusation was a story in which she was in the kitchen while someone else was killing Meredith. She would have been guilty in that case too. A person doesn't need to be physically in the murder room to be guilty of murder.