Earlier quoted context omitted.
That depends entirely on seating capicity and layout and specific numbers. Also whether male across aisle, male in seat ahead or behind is considered an issue. It's a constraint problem similar to paying extra to not be near children.
What is more expensive? Not having to sit next to a child or not having to sit next to a man? Also: will IndiGo Airlines share with me, a guy, part of the extra money I help them make? ;)
Block seating isn't hard to work out.