Why is a tweet from Clark news?

Stuff reports:

Former prime minister Helen Clark has criticised remarks made by NZ First leader Winston Peters in the House on Tuesday.

Peters was rebutting Pāti Māori co-leader Debbie Ngarewa-Packer about “ongoing colonisation” when he said it was “a retard comment”. …

Clark reposted a clip of the comment on social media, saying it was “Distressing to see this kind of language/attitude in NZ Parliament”.

Why is this a news story? Helen Clark tweets many times a day on various issues. She has not been Prime Minister for 16 years.

As to the substantive issue, I’m not clear whether Peters is being criticised for being inaccurate with his description, or for being insensitive with its use!