When are people going to get that racism toward indigenous Americans is racism just like any other racism?

Over on Ohdeedoh, which I usually like (aside from some of the classism and the overgendering of children that usually pops up on shopping/decorating blogs), there's a post about how someone threw their kids a "teepee party," complete with a cake decorated with plastic models of poorly stereotyped Native Americans. The post on Ohdeedoh states that this was a great party idea because "kids love playing in teepees." Sure, most kids do love homemade forts of all kinds, and I think that a plain teepee without any racist imagery on it is a fine toy for children. I'm just not sure how this leads to the conclusion that children therefore also need racist depictions of teepee-dwelling people in order to get the most out of the playing in a cone of fabric.

How the hell did someone think that's an appropriate thing to do, and how did a fairly savvy website think this was OK to post? I'm guessing Ohdeedoh wouldn't post about a party where people dressed up in blackface and decorated the yard with images of negative stereotypes of Black Americans, so why are Natives an acceptable target of objectification?