Yes, EBT is not secular Buddhism at all. EBT is just text (s), not the word of the Buddha. Some EBTs are edited early, some later, and all are sectarian texts. But according Ven. YinShun, SN/SA is the earliest collection of the four Nikayas/Agamas in Early Buddhism.
Cf.:
Pages 2-7 from The Fundamental Teachings of Early Buddhism Choong Mun-keat 2000.pdf (440.2 KB)