dadāti pratigṛhṇāti guhyam ākhyāti pṛcchati bhuṅkte bhojayate caiva ṣaḍ-vidhaṁ prīti-lakṣaṇam

The words bhuṅkte bhojayate indicate that one should eat with devotees. One should carefully avoid eating food offered by nondevotees. Indeed, a devotee should be very strict in not accepting food from a nondevotee, especially food prepared in restaurants or hotels or on airplanes. Srila Nityananda Prabhu's reference in this connection is meant to emphasize that one should avoid eating with Mayavadis and covert Mayavadis like the sahajiya Vaisnavas, who are materially affected.