He could not rely on the Christian Armenian potentates of Transcaucasia, since they were branded as heretics by the Orthodox Church, and even the king of Iberia preferred to befriend the religiously tolerant Persians.
Since he couldn't trust the Christian Armenian rulers of Transcaucasia due to their status as heretics in the eyes of the Orthodox Church, he opted instead to form friendships with the more accepting Persians, even going so far as to befriend the king of Iberia.