if the bullyings stopped and uichi is no longer suicidel what is the point of continuing to rewind
Because Yotsuha's surgery will leave her bedridden/immobile for "a long time", implied to be the majority of those six months she took before reuniting with Uichi in the original timeline.
That's six months during which Clover can act against Uichi without Yotsuha's interference. Clover's already gone so far as to guide Yae in his hostilities and manipulate Utako to the point of destroying the family's financial stability. Theoretically Yotsuha's aid and support up until this point would give Uichi the mental fortitude and stability needed, but there's no telling how Clover could escalate while she's powerless to do anything.
There's also the simple fact that this person is after Uichi's life. Sure they're fixated on specifically making him kill himself... but anyone who watched Criminal Minds knows that individuals like Clover could change their MO as they escalate/deteriorate. What if they jdecide to say "fuck it" and decide they just want Uichi dead, period?
Uichi's safety and happiness are paramount in Yotsuha's mind. We've seen her rewind after getting Uichi's family ejected from his life because it clearly made him upset, even if pragmatically she could have simply supported him until the pain faded. She's aiming for that golden ending and she'll save scum as many times as it takes to make it happen.