There are a couple of problems with this photo of two air force members (makes no difference if they are guard, active-duty or reserve).
First, I don't have a problem with anyone breast-feeding kids where ever the opportunity presents itself as a necessity.
However, the two people are out of uniform; in public. There are a lot of things that are not in the regulations/instructions on wearing the uniform. So, stating that the regulation or instruction says nothing about breast-feeding is a dodge. The regulations/instructions are clear about what defines correct uniform wear. Also, they are outside not wearing a hat. There is no indication that is a posted no-hat area. Strike two.
What is sad is the person on the right is an NCO and should know better. If one is unsure of why they have to wear the uniform a certain way or think they can freelance to suit themselves, maybe they do not belong in the military.