I'm not getting your criticism of the Labour party here, NS.
The report linked has both Yvette Cooper and Alex Davies-Jones acknowledge that it is an "appalling joke" and "banter".
So they did say it was a joke in the article you linked to.
And the last line is surely correct:
"The 'banter' needs to stop and it has to start at the top."
Which is surely exactly what you argued for with this:
They should have said we know that it was a joke, we know he didn't mean it but he's Home Secretary.