I agree with neverplan.
I never think you should judge someone by something you saw on one particular day.
My daughter is 21 months and will have the occassional sip of softdrink (including coke) out of my glass. If I was having a particularly bad day and she was whinging for it, I probably would put a tiny bit in her sippy cup for her to have a minute of peace. On the odd occassion, I don't really see anything wrong with that.
She also has a pop top drink every day and cordial with no added sugar.