Yeah, treating neoplatonism as a heresy is a weird choice. The neoplatonists were a subset of Hellenic Pagans, and were not seen as heretical in any way. Julian was hailed as a hero by the pagans of the late empire, not just by the Neoplatonists, and his views were actually quite traditionally pagan on many things. For example, the personal gnosis he often experienced in the form of visions, was not particularly Neoplatonic.