"God save our country if this is the culture and behavior of our MPs," Shiv Kumar, 60, writes, describing his assault.
Mr Gaikwad has not just refused to apologise but has also complained to Civil Aviation Minister Ashok Gajapathi Raju of "poor service", alleging that it was the manager who misbehaved.
Mr Kumar was called in when the Sena lawmaker refused to exit the plane after his flight from Pune landed in Delhi around 10.30 am on Thursday.
Mr Gaikwad was furious that he had to fly economy despite a business class ticket that MPs are entitled to. He refused to accept Air India's explanation that morning flights are mostly all-economy.
Describing the incident, Mr Kumar writes that he told the politician 115 passengers were waiting to board the aircraft for their flight to Goa. But Mr Gaikwad insisted on seeing the "top management" and held up the plane for nearly an hour.
"He became abusive and used foul language. When I spoke to him in English, he told me to speak to him in Hindi and when I started speaking in Hindi, he used foul language and bad words against me and started beating me... Took out his slipper and started hitting me... The staff, who were present, tried to save me. He also tried to throw me out from the step-ladder but the staff prevented him from doing so," he writes.
Mr Gaikwad "... broke my specs and tore away the buttons of my cardigan and I was humiliated in front of the crew, security staff and the cleaners," he says.
The first-time parliamentarian from Maharashtra bragged that he beat the staffer "25 times with his slipper". Today, he said it is the employee who has to apologise, not him.
Air India has filed two FIRs or police complaints against the lawmaker and is considering a no-fly list to keep out unruly passengers.