Were these documented interviews?
I have no doubt that there may have been rogue individuals that destroyed artifacts/architecture, but I find it hard to believe that this was sanctioned. Especially by the Smithsonian.
With regard to the mounds being destroyed. Many of these mounds are located in areas close to large rivers and lakes. Nature itself has destroyed many of them, and man just finished the process. The mounds near Ashland Ky, are a prime example of this.
Also, many of these mounds are on privately owned land, and controlled by their owners, and not a museum or park service.
“Most of the mounds in Mississippi, however, are on privately owned land. As a result, many mounds have been irreparably damaged or completely destroyed by modern development and looting.”
or
“Of the 23 mounds originally present, four were destroyed and several others reduced to remnants by agriculture and excessive grazing prior to the site’s acquisition as a state park.”
nps.gov/nr//travel/mounds/textonly.htm
and
Another regional site is the Forest Home Farm Site Complex in South Portsmouth, Kentucky about 33 miles west of Ashland, Kentucky. It is across the river from Portsmouth, Ohio in Greenup and Lewis Counties, Kentucky. This site is located on a family owned farm. You must have permission to visit it."
library.thinkquest.org/CR0212160/Regional%20History.htm
Again, I don’t doubt that these things have been destroyed, that is obvious. What isn’t obvious is that it was sanctioned in any way by the Smithsonian.
If these “interviews” weren’t documented, they are just hearsay, and carry little to no weight at all.