Joseph,
Avram, someone not infected with the perverse mores of secular society would consider a woman in a short sleeve shirt in public as severely worse than a woman publicly nursing in the open?
Provided we are not talking about a “wild eyed” activist as Gadolhadorah described above, yes. Most women, Jewish or not, are uncomfortable nursing in a public place, and try to do so as discreetly as possible. One would have to be invading her space terribly to see anything problematic. There is no flaunting going on. If airports, restaurants, waiting rooms, etc. had clean, comfortable, and private nursing spaces available, I think the vast majority of mothers would happily take advantage of them.