There's no real formal definition of crisis, but being fair to him it's not yet a crisis. It is however a sharp devaluation, and appears to be the opposite of what he was predicting.
He's saying that a devaluation won't kill the country because the debt is denominated in Pounds.
That seems like a strange clarification. If he's predicting the Pound wouldn't decline - he'd say that.
Not say that if it does decline, it won't be a problem...
That implies it's a possibility. It just won't cause a crisis if it happens.
https://twitter.com/paulkrugman/status/1573656086716071937
"The moron risk premium has now been priced in". That is, he believes the currency depreciation is substantially over.
He is also saying the thing you're reading him as saying too though.