He can counter claim for the damage but not for slander in this particular way. He will have to open a fresh case at a huge cost which wont happen.
Threatening behaviour is not a concern of the civil courts and racism is the universal allegation that is always trotted out only really second to domestic violence or sexual abuse. I wouldn't worry. That nonsense doesn't defeat a legitimate claim.
Can I clarify anything for you?
That said, you can't get the counter claim struck down because the claim for damage is legitimate.
Yes, of course he is. We can all avoid paying our bills if we accuse everybody of racism and domestic violence and generally make allegations that somebody made a pass at us one hundred years ago.
He can bring a counter claim just like you can bring a claim. He will have to prove it.
Dont be deterred by this. Ridiculous counter claims are put in all the time.