Stripping the York daughters wouldn't enable King Charles to avoid allegations of racism against the Sussex children. Following the Duchess of Sussex's interview with Oprah Winfrey, online discussion was replete with allegations of racism based on Archie being born without a royal title, despite the Wessex children, the Phillips children, the Snowdon children, and numerous other children of princes and princesses of the UK being in the same condition.
Besides, as matters currently stand, one could point at Princess Eugenie being the one other member of the royal family who recently has been visibly close to the Duke and Duchess of Sussex and allege that the stripping of the York daughters was an extension of anti-Sussex bias.
It would be off-topic and against forum rules to discuss other debates about the Sussex family, so suffice it to say that there have also been allegations of racism and Cambridge favoritism based on entirely different matters, and in order to avoid all such allegations the King would need to offer the Sussex branch not only titles but security funding, etc. equal to the Cambridge branch.