Bottom line: stop putting the burden of your discomfort on to the mother, they've got more than enough to deal with already.
All well and good provided that the mother doesn't expect the passenger next to her to avert his eyes while she breastfeeds. In these days of #MeToo I hope that she doesn't expect him to keep his eyes closed when her breasts are exposed in front of his face. People get into trouble for less than that.
This is a case of a mother feeding a baby, not a stripper swinging around a brass pole.
If a person gets their rocks off on that, it's on them, not on the mom.
But yeah, try making a move on one of the nursing moms I know who also teaches women's self defense, and she'll have her foot in your balls before you know what hit you.
Why is it too much to ask people to act like an adult and show some consideration for a nursing mom?