Running with proper form might help your knees (and it provably doesn't hurt them). The actual science your source is drawing from will tell you that it's not conclusive that running improves knee health [1]. Running with poor form will definitely damage them. Walking (2.5mph, briskly) will not hurt your knees and is considered overall one of the best exercises you can do [2]. Walking and running (with proper form) both will improve knee pain.

1. https://pubmed.ncbi.nlm.nih.gov/18550323/ 2. https://health.gov/sites/default/files/2019-09/Physical_Acti...