The Muslim radicals had attacked the professor as a punishment for the alleged reference to Prophet Mohammed in a question paper that he prepared for an internal exam in 2010.
The two accused, who hailed from Thalassery, were handing out pro-Maoist pamphlets and shouting pro-Maoist slogans when they were arrested from the Pantheerankavu market.
NIA has filed a charge-sheet against 11 accused persons with links to Khalistan terror, including a British national in connection with the murder case of Punjab unit RSS vice-president Brigadier Jagdish Gagneja