1. Its written specifically to incite and belittle.
2. The writer bears an uncanny resemblance to the head orangutan in the original Planet of the Ape movie.
On the merits of the underlying issue, I can't see a problem with monument to the Union dead, although I get the strong sense that this newspaper hack considers the Confederates to be equivalent to SS. What personally motivated Confederate soldiers was clearly not slavery (very few owned slaves and their letters indicated that they thought little about the issue), although it is hard to imagine the war developing without the underlying issue of slavery.
Not really accurate.
Here's a link to the percentage of slaveowning families in southern states per the 1860 census. MS was 49% and SC 46%.
http://civilwarcauses.org/stat.htm
The claim that only 6% (or whatever) of southerners owned slaves is technically accurate, in that title was usually vested in the head of the house, thus wife and children were not technically slaveowners. The problem with this is that by this definition Scarlett O'Hara would not be considered a slaveowner, since her father probably had title to the slaves in his name. But that certainly isn't how Scarlett would have thought of herself.
Here's another link to a discussion of slave owning among CSA soldiers. Slaveowners (in their own name) were in a decided majority among officers.
Fewer enlisted men, being on average considerably less prosperous, owned slaves in their own name, but more than one in three came from slaveowning families.
http://deadconfederates.com/2011/04/28/ninety-eight-percent-of-texas-confederate-soldiers-never-owned-a-slave/
I don't know what you classify as "very few," but to my mind more than one in three to more than one in two doesn't qualify.
BTW, this correction aside, I agree with your post.