I have a big dog that my Yorkies dearly love and Boo loves the Yorkies.....
When I am out and there is even a medium sized dog around, I snatch up the yorkies. I try to be discrete, but the safety of my Yorkie kids is #1. If someone wants to get offended, that is their choice
On the other hand, I would EXPECT someone to pick up their little dogs if I was walking Boo -- not that Boo would cause any problems, but I would like to see the owners concerned enough about the safety of their kids to pick up first and ask questions later