Posting dozens of "You are too thin" "You look unhealthy. You don't look good" comments under someone's social media is not worrying about someone, it is actively harming someone. These type of comments are harmful especially for people who have a past with EDs, those type of comments can trigger attacks and can cause a downward spiral. Any ED therapist or person who has struggled with EDs can tell you that. People do not realize what harmful language they use in their daily life that can cause someonelese's ED to be triggered and it is most often those people who "worry" who do the most harm, because they use the wrong language. You can express your worry about someone without attacking or scrutinizing their body or using negative words in association with their body.
Zhenya has been struggling with her injury for a long time now, it is obviously stressing her out and she is in pain, let's not forget that. She has a medical team around her who help her to recover from that. Someone's back does not magically heal over night, nor does the stress magically disappear over night. It is good that they are taking things slow. Posting those type of comments won't help her, it will harm her more and will stress her out.