There is a vast difference between memorializing the dead and memorializing the cause. The Civil War entailed a horrific loss of life, which should be remembered. However, memorials should not celebrate the evil cause in service of which the Confederacy fought. Bridges and streets should not be named after those who sunk this nation into war to preserve slavery. Politicians and citizens should not be celebrating this Lost Cause while working to disenfranchise the descendants of people their ancestors went to war to keep enslaved.
If the Vietnam memorial said “We’d do it again, because napalm is awesome and if we’d stayed longer Vietnam wouldn’t be Communist today!”, I’d absolutely support the defacement of that memorial. But it doesn’t, it simply commemorates the dead and is rather neutral on any other topic (not least, noting that Vietnam is not Communist today). The dead matter, not the lying cause.
If a (hypothetical) Iraq memorial said “We’d do it again, because our leaders didn’t lie to us and we totally found WMDs!”, I’d absolutely support the defacement of that memorial. The dead matter, not the lying cause.
This is a memorial celebrating those who attacked first at Fort Sumter to start a civil war (or, if you want to be weaselly, died later trying to prevent it being retaken). It sits under a Confederate Flag symbolizing racial terror that continues to this day. It sits in a city bursting to the seams with celebration of crime and treason in defense of slavery. It sits in a state whose legacy of toxic racism is a matter of public record and history. It sits in a nation where so many people deny any racism exists at all (unless it’s towards white people!), while turning a blind eye to police brutality, the suppression of voting rights, and systemic economic inequality.
The dead matter, but too many Americans still believe in that lying cause. That memorial, in all the context noted above, says “Slavery and racism rule! We were right, and we’d do it again in a heartbeat!”. I don’t even have to infer this — we have politicians from multiple states who are still campaigning on racist brutality and yes, even secession!
So do try to be a bit more clear on just what this vandalism was actually trying to point out. You seem to think it’s strictly about mocking the dead of the past. If that were true, I’d feel quite differently. But clearly, it’s not about mocking the dead. It’s about drawing attention to the suffering of the present, and how the living are still deeply wedded to an evil cause.
Have a nice day.