The activist Mallikarjun Bhaikatti had, through an RTI query, revealed that around 14,000 sq feet illegal construction was carried out in a four-storeyed building and boys hostel on the Latur-Nanded road.
Bhaikatti had addressed a press conference at Latur on Thursday to "expose" the illegal construction, police said.
The Sena workers brought Bhaikatti to the college premises on Friday when around 4,000 students were present and assaulted him with an iron rod, before blackening his face.
The injured RTI activist has been admitted to a hospital in Latur.
Local Sena activist Abhay Salunke said Bhaikatti was a "blackmailer".
Earlier this month, Sena workers had blackened the face of Sudheendra Kulkarni, chairman of the Observer Research Foundation, in an ink attack ahead of the launch of 'Neither a Hawk Nor a Dove: An Insider's Account of Pakistan's Foreign Relations' authored by former Pakistan foreign minister Khurshid Mahmud Kasuri.
Image: Mallikarjun Bhaikatti. Photograph: Twitter