Because at the time of the screening they didn't know that Coll's star of David tile was bunk.
The documentary is still on their site. Therefore, the Smithsonian has recognised that a mistake was made, but it was not such a serious mistake as to make the entire work bunk. Experts know they make mistakes, it is the seriousness of the mistake and why the mistake was made that is important.
By continuing to host the documentary on their TV channel, the Smithsonian have shown their support for the work done at TII. You lied when you said "Uh-huh and experts at the Smithsonian declared her work to be bunk". There is no evidence of anyone from the Smithsonian saying anything like that. You liar.