Excellent point, Megan. This posturing and harrumphing will not make a blind bit of difference.
No one will follow his lead, particularly in the global South and Europe. If the government of the UK even breathed the notion of sanctioning an internationally recognised body like the ICJ, Starmer would be toast.
Burnt toast.
So just sit back and be entertained by the hilarious sight of the modern day Don Quixote: DonTrump, tilting at windmills.