I'd say ebay didn't remove it because the comment itself is a strange one. It starts out well with 'Makes putting on compression stockings much easier' but ends in 'though you do III'.

That word 'though' implies there is a negative somewhere on the way. What it is, I do not know as the buyer didn't finish the sentence. I can't make any sense of it anyway and I have had decades of experience reading prep writing. My guess is the ebay rep feels the buyer was unhappy about something, so they are letting the neg stand.

Your buyer isn't going to do anything. They don't want the hassle. If they couldn't be bothered finishing the sentence, they are certainly not going to put themselves out by investigating how they can revise their feedback.

Unfortunately, seller feedback is often degraded by half wit buyer comments. I've seen it over and over again. Buyers who give a neg and say something like 'good'.

Sometimes ebay will remove negs, sometimes they won't. You could try again in ebay chat, see if a different rep will do anything.

On the plus side, most reasonable buyers with more than a couple of brain cells can see when feedback is unfair or unwarranted and will ignore it. I see you answered the neg. If I were buying from you, I certainly wouldn't be turned off by a neg from a buyer who gave a mostly positive comment and didn't explain why they rated it as negative.