They do that because the attackers are the ones they politically align with. The situation in DRC is complex; the Bantus have a deep hatred for the Tutsi, and the Tutsi inhabitants have been receiving a lot of issues to the point where their nativity is questioned. The government is always giving them lip service into recognizing them as having their own territory but no actions come from it.
The paramilitary rebel groups that are powered by Rwanda are committing atrocities toward the Bantu inhabitants. I think that includes Hutu rebels. The Banyamulenge are getting discriminated against while the Rwandan politically charged groups are doing a lot of killings, and the Congolese Bantus are getting extremely xenophobic, and the local Tutsis sort of have to rely on the Rwandans that do dirt to protect them. It's very messy and unfortunate.