It's an assumption to state that it would take 20 minutes. Sometimes all my DS needs is a 5-minute "fix" so we can get from one place to another where I can feed him more comfortably.
Also, I happen to take a LONG time trying on clothes. I am picky. No one has ever rushed ME, no matter WHAT my reasoning for taking a long time.
I think it most definitely has to do with a prejudice against BF.
I'd like to think that if this had happened to me I would have said, "I'll be out as soon as I am done soothing my baby and am able to dress, we'll discuss your issues with breastfeeding when I am done." I tend to be a little bit of a brat when it comes to people telling me I can't do things. Sucks that anyone would have to stand up for their right to sooth and feed their child.
I was going to email the store but they don't have a link to email on their page. I was thinking maybe I'll mail her the breastfeeding symbol to put in her window.