"She (the flight attendant) says, 'well, look, again airway regulations, you cannot sit in an exit seat, if you're disabled or, you know — or if you require an extended seatbelt'," Mr Beales told Today.
Mr Beales earlier told the Geelong Advertiser: "I can fit into the seat fine — I didn't need a second seat.
"It was fat-shaming. She was rude."
The Civil Aviation Safety Authority provides guidelines to Qantas about safety in the emergency exit row and recommends passengers seated there are "able-bodied" and capable of helping in an emergency.
Passengers who buy seats in the exit row are asked to adhere to a range of criteria when they book.
"If passengers are unable to meet this criteria, airlines including Qantas will ask passengers to change seats," Qantas said in a statement to news.com.au.
"Customers who purchase an exit row seat are told they must satisfy the requirements during the booking process."
"It made me feel really belittled. I could have helped in the emergency," said Mr Beales.
Qantas's website says passengers who need an "extension" belt should not be seated in the exit row, which is consistent with other Australian airlines.
Mr Beales took up the issue with Qantas's customer service team and news.com.au understands they have reached out to him.