When people are passionate about something they will not change their minds and will defend their opinions to the death.
Cat owners, parents (I found this out), dog owners, whatever.
I own 2 Rottweilers and will argue til blue in the face with any numpty who tries to tell me they're savage. Same goes for cat owners being told their precious pets are dirty buggers or parents being told that there can be life without children.
However it does seem clear that the answer to the question is undoubtably YES. I have no issue with a cat owner defending the rights of their cat. But if my cat was crapping in someone else's garden and couldn't be stopped, then I'd go over every week with a poop scoop and offer to clean it. Is that so hard? I agree that cats can't be trained as well as dogs etc but if my dog craps in the street I lift it!
This attitude of "my cat can dump where he/she likes and it's not my responsibility" is the same as some parents who let their children run riot and defend them when they do wrong, the "my wee jonney wouldn't do that" syndrome.
Like I said, I fit into the category of those who will defend my dogs, but if the dogs showed agression to anyone, I'd deal with it. Not just sit back and say "oh my dogs are fine, it's not my responsibility".