There is this concept I learned about in a sociology class one time, it's called the Birdcage Theory (or something like that). It says that the first time something happens (like a racist remark, for example), it might not be such a big deal. You can think of it as one wire. But, when they keep happening, the wires start building up and eventually you can have enough wires to create something around you like a birdcage--which ends up being a really big deal, b/c then you're trapped. It's supposed to illustrate how oppression builds up over time and can eventually handicap.
This is how I see the OP's story. If this mom were the exception rather than the norm, it wouldn't be a big deal. But, the norm in this culture is to push formula on babies--and there are a lot of shady, crappy, insidious ways that this happens. So, the wires build up, and there are more and more times when formula becomes the norm and bfing becomes something Other (something too hard, something radical, something *other* than the norm). And it's hard not to reach a threshold and want to push back. And how do you push back on a cage? You can sometimes only touch a couple of wires at a time. And sadly, it often ends up being the mom in the OP who gets the brunt of that, know what I mean?
And it's not really HER. It's not any of the moms here. Hell, it's not even *just* Nestle. It's the WHOLE DAMN THING--ALL the crappy formula reps and ALL their employers, the Gary Ezzos, the pediatrician who gives you shit, your MIL who keeps tsk tsking, the jerk at Burger King who tells a woman to get out or cover up, the barrage of media images showing bottles, the people who roll their eyes whenever you mention that you're "still" nursing, the misinformation and total bs that we've all heard over and over again about bfing and breast milk, and on and on and on.
So, of course we should support a mom who is doing the best she can. Of course! But I know how hard it can be to see that part of it, and to focus on the fact that one more wire is coming at you and just how much that sucks. I get the 'enraged' part of it. I don't think the OP was enraged AT that mom, so much as enraged by the whole birdcage. Does that make sense? And I don't want to put words in anyone's mouth, but for me, I've really been thinking about why scenarios like this bother me so much--and this is kinda why.
I hope I explained it OK and didn't overstep my bounds re. the OP. I also don't want to add to the negative feelings that people are having here--just hoping to bridge the gap there seems to be in our different experiences and perceptions.