First, the report does not say that he definitely was not radicalized at UCL. It says there is no evidence that he was radicalized there. So they are not saying, "no, it did not happen". They are saying, "we do not know".
Second, this report saying "no evidence of radicalization going on at UCL" was commissioned by UCL itself.
Universities work very, very hard to protect their image to keep up the flow of new applicants and donations. This reports stinks of a PR whitewash job.