Indians could've loved The Searchers for several reasons. Because the Indians in the film came off better than the John Wayne character. Because the film exposed the racism inherent in our culture. Or simply because they finally saw themselves on the screen in any role, no matter how unrelated it was to their actual lives.
None of this has anything to do with the quality of The Searchers, which was the writer's point. Regardless of its racism, the film is highly overrated.