He's being used to merely reinforce the establishment Overton Window on Ukraine. If Russia is "... wrong at every level" then its opponents: Ukraine and the West are by inference clearly "right at every level"
It doesn't matter about the nuances of the situation given in the body text; many of which from his Corbyn has tried to talk up, its the quote they were after.
There's a clever quip attributed to US political pundit George Will which encapsulates the modern political media world of headline soundbite and spin- something that Corbyn never quite "got":
"If you’re explaining, you’re losing...’
-It should be his epitaph.