Considering that the form pārppār often occurs as pāppār, clearly even as late as 9th century 'pārppāṉ', its singular form, must not have been restricted to refer to brahmins.[...] if one were to consider the term 'pārppāṉ' linguistically, we see that the usual interpretation that it referred to brahmins as seers based on 'pār-' 'to see' (as implied by DEDR 4091a and b as given below) is unwarranted.
Without more information about the socio-linguistic situation of the early periods of the Indo-Aryan and Davidian interaction, I think, we cannot easily determine if pār (-pp-, -tt-) 'to see' is related to pā(r)ppāṉ 'Brahmin' or not.1. I believe pār (-pp-, -tt-) 'to see' is unrelated to pā(r)ppāṉ 'Brahmin'; Although DEDR grouped them under the same entry (4091a and 4091b), I am not very sure if we can make a semantic connection of 'see' with 'seer' in Dravidian.2. CDIAL entry 9327 shows Pk. baṁbhaṇa,S. ḇã̄bhaṇu, kal. baṁbhana, OB. bāmbhaṇa, Or. bāmbhuṇa, bābhuṇa, Bi. Mth. bābhan, Bhoj.bāmhan, bābhan, among other reflexes. We cannot ignore the close similarity of these reflexes with Te. bã̄pãḍu, Ta. pāppāṉ.3. I think you would agree that connecting pōṟṟi/pōṯṯi with pā(r)ppāṉ is a bit far fetched.
Regards,