I don't know how large your local paper is; my experience with larger papers is that they verify the author to at least a basic degree (believe me, the items I was writing about are not nearly as contentious as the matter at hand here, nor am I in a position akin to the rector's.) And in a situation like this, there would certainly be a correction if the rector claimed the letter wasn't his, and no such correction appears. As such, that the rector made the statement seems to me quite adequately sourced, even if the claims he makes are not. However, if you would like to slightly reword it to make it even clearer that the rector is making claims that are not otherwise in evidence (replacing stated with claimed or asserted), I would not have an objection.
I think the claim, even if treated as true, is not much of a claim; the count of accused priests has an invisible "yet" hanging over it, as more recent graduates would have had less time to have accusers come forward than those from previous classes. And I think the reference is good to have in there for something it -doesn't- include; the letter is essentially a "yes, but" note rather than a "no" note, as it doesn't deny anything in the Times article and thus to some degree blunts any objection that it's just the Times reporters say-so.