According to Osho, Brahmins split because true Brahminhood is realized, not inherited. The awakened, who knew Brahman through self-knowledge, recognized Buddha as the flowering of Brahman and bowed, becoming his close disciples. The counterfeit—Brahmins by birth clinging to ego and status—felt threatened by his challenge to lineage-based authority and therefore opposed him.
Real Brahmins who knew truth saw Buddha and followed him; fake Brahmins proud of birth felt threatened and fought him.