It’s pretty clear you haven’t actually looked into Osmanagić or his theories if you think that they simply say that Bosniaks interacted with aliens. He claims that they are the descendants of aliens and ,more importantly, that civilization itself originated in Bosnia and Herzegovina and Bosniaks are the oldest inhabitants of the Balkans. (And by oldest civilization, I mean way oldest, as he claims that the so-called pyramids in Bosnia and Herzegovina were built during the Stone Age.) Nevertheless, those latter two ideas are precisely why his theories have been proven so popular with Bosniak nationalists. Nationalistic pseudohistory exists everywhere, but it’s especially popular in the Balkans, with each ethnic group trying to prove that they were the original and most ancient inhabitants of the area. Though Osmanagić himself does not appear to be a Bosniak nationalist, it’s not surprising that his theories have been embraced by them.
Conversely, the theories of Däniken and Tsoukalos about Aztecs, Maya, Egyptians, Polynesians, and more interacting with aliens don’t offer anything nearly as appealing to their modern descendants. What’s more, though I doubt it was intentional, their theories come off as uncomfortably similar to 19th century racialist ideas about how everything from the pyramids to Great Zimbabwe were built by White Europeans. I mean, Däniken and Tsoukalos could potentially claim that ancient Egypt and Mesoamerica were cradles of civilization, but that’s already accepted by mainstream history and archaeology, so they wouldn’t be offering anything particularly new.
To be fair, Osmanagić does try to present Maya as part of an advanced alien race, but I suspect that the reason that a lot of the modern Maya aren’t embracing him with open arms because he is under the impression that the Maya no longer exist.