Unless there’s a proposal for building an “un-monument”, when we put up a statue for a bigot who did a good thing, we’re elevating the good thing without the context of the bad.
We should celebrate that FDR’s policies got us out of the Great Depression, and also never forget that he signed off on internment camps.
But in practice, raising a statue of somebody raises that person. They’re put forth as the face of the accomplishment, and they’re more than just the accomplishment. Else we’d just raise a tower with the inscription “In recognition of the British spirit, and of the lives lost protecting us from Naziism”
My broader contention is that you don’t need a statue to celebrate the accomplishment, we have plenty of other ways to do that. So when somebody says “hey, lets take down this statue because the person in it did some pretty bigoted things”, the only thing fighting for keeping the statue is inertia. Nobody in the UK is going to forget defeating the Nazis, every other building is inscribed with details about what stood there before the Blitz.
"we shouldn't celebrate bigots" is reductionist because it narrows important people down to a single dimension. That's puritanism - if somebody invents a cure for cancer and saves billions of lives, they should be celebrated for that achievement even if they have bad racial views, because from a consequential perspective people want to be celebrated and are inspired by the idea of being considered a hero for breakthroughs in their field. You can simultaneously celebrate and condemn a single person, it's called nuance - and the conversation around an individual is not solely shaped by the placard on their statue.