Well, needless to say we've had our share of going to dog parks and the girls love it!
Now I think if I had small dogs like Chester or Millie I probably wouldn't take them. There is a good chance of smaller dogs getting hurt easily.
I know when we went to the Michigan dog park there was a small dog (can't remember what kind) and a lady is yelling "Who does this chow belong to?" Well of course, it was me She said Huney "attacked" her dog. Now I know this is not true, it's just Huney's way of playing. She has a low growl and grabs their legs. To her it's all in good fun. But then again I understand the lady's feelings. Her dog was much smaller than mine (that's why I wouldn't take small dogs to a park with much larger dogs).

But in answer to your question, I think you are being a very responsible dog owner. Your dog listens and does what you tell him to.
I agree, this lady is a moron & someone should tell her how stupid she's being.