I can see how it reads funny to civilians but it's a reflection of the fact that the BBC gave Pink News owners a right of reply and they chose to hold that convo off the record (source: I own my own PR business, 35 years experience).
So when an investigation like this happens, the BBC will give the subjects a right of reply: 48 hours (24 if you're unlucky) before publishing they'll send the subjects an email outlining the allegations and ask for their right of reply, either on or off the record. Usually the subject then spends those 48 hours in a panic, consulting with lawyers and people like me. Usually when I'm advising clients, I'll recommend they lay out a brief response on the record, but in this instance it looks like the couple's representatives (probably PR rather than legal) chose to have an off record convo with the BBC journo (which is in itself a sign of panic about future lawsuits and revelations).
The off record conversation would have gone something like this:
Journo: "So these are the allegations, do you have an on the record statement you'd like to provide us?"
PR rep: "Not at this time no"
Journo: "OK but can I at least put what your position is on these allegations - are they true or false?"
PR rep: They're false
Journo: OK so you're saying that the allegations are false?
PR rep: Yes
And then, because they answered Yes but the convo was off the record, that's why the response was framed that way by the journalist.
I'd like to reiterate that it's extremely unusual for a decent media org not to be able to come up with an on the record statement refuting the allegations, and does suggest to me that there's more/worse to come. And that lawsuits are cranking u behind the scenes.