First of all, how does materialism "dismiss and erase" indigenous knowledge? Most materialists (Marxists) are in favor of recording, recovering, and rejuvenating indigenous culture and knowledge. Those who aren't, are anti-Marxist and should not be taken seriously. That being said, a rejection of materialism and science like this is also completely nonsensical and is an attack on the very fabric of Marxism and Scientific Socialism.

Yes, I ageee - something being accepted as "fact" can be used to reinforce oppressive power structures, such as patriarchy, slavery, etc. - however, using this as justification to reject science, materialism, and "objectivism" makes no sense. Pseudoscience like eugenics and other forms of "scientific" racism were used (and are still being used) to reinforce horrible oppressive and colonial power structures. But using the horrors commited as a result of pseudoscience - which is a rejection of actual science in favor of theories that lack proper evidence and are not backed by any real science, as cause to reject science, is self-contradictory and oxymoronic.