According to Osho, he called Shri Poonamchand-bhai a fool because Poonamchand took sannyas for the wrong, worldly reasons—hoping for a miracle cure for his eyes—then abandoned it after projecting a 'be free' message onto a photo, freeing himself only from sannyas while clinging to wife, wealth, fears and superstitions. He thus became 'free of freedom' and tried to justify it intellectually.
He chased a miracle, misunderstood ‘freedom,’ dropped the path meant to free him, and kept all his attachments—so Osho called that foolish.