Gst applicability - education

Am rephrasing an earlier unanswered query on GST applicability, hoping for some clarification:

(i) Do Visiting Faculty (honorarium paid per hour taught basis) of PG programs of Management Institutes (Not IIMs) have to be registered under the GST Act, if the total amount earned by them per annum exceeds Rs 20 Lacs?  

(ii) Is there any ambiguity about this aspect or is this absolutely clear in the Act?