[The Buddha said to Sāriputra:] “Sāriputra! In the chaos amidst the turbidity of age, sentient beings are mired in heavy defilements, greed, and jealousy and develop unwholesome roots; therefore, with their powers of skillful means, the Buddhas distinguish three vehicles within the single Buddha-vehicle. Sāriputra! If any of my disciples declare themselves to be arhats or solitary-realizers, but do not hear or know that all Buddhas-Tathāgatas teach only the bodhisattva doctrines [that transform sentient beings into bodhisattvas], they are not true disciples of the Buddhas, and are not true arhats or solitary-realizers.
The Lotus Sutra
Translation of the scriptural passage referenced the rendition of Gene Reeves. [Reeves, G. (2008). The Lotus Sutra: A Contemporary Translation of a Buddhist Classics. Boston: Wisdom Publications, p.85]
This passage confirms that those who claim that the Great Vehicle is not the Buddha's teaching are definitely not Buddha's disciples; nor are they arhats or solitary-realizers. They certainly cannot be enlightened bodhisattvas.
A Discourse on the Lotus Sutra, Vol. 2, p.327