I suspect this is rumour rather than news and something so extreme would surely have become common knowledge by now and would presumeably have been an upset caused by extreme weather.
From a technical pont of view I wouldn't see why this should not be perfectly possible and if handled smoothly should have no adverse impact on the aeroplane - other than the mess that would have to be cleaned up from the pax !!!
I have seen video of the original 707 - the venerable Dash 80 - being put through a compete barrel role during one demonstration flight some decades ago.
I understand that the test pilot flying was quietly taken to one side and asked to refrain from further performances.
DGG