It wouldn't have occurred to me to do it. I'd be walking the halls with a screaming child and then later going *doh* I could have just put her on the boob.
I remember how protective I was about the bond between me and my babies but TBH I don't think that a bit of a breastfeed would break that bond. I think that the breastfeeding Mother handled it wrong - we all have mobiles these days so she could have rung and said I've got a full boob and little Timmy is screaming. Do you want me to whip it out? Then the Mum of the child could have made the choice herself and everything would have been sweet.

It's not like she abused the child - I'm sure she acted out of compassion and sharing so not talking and continuing awkwardness just seems like a bit of an extreme reaction to me.