Quite a lot of arguing on this thread.
The fact is, there are poor teachers who go unchallenged and there are good teachers who are hauled over the coals for no good reason.
Based on the information given by the op, I as a teacher would regret the time spent and pain suffered with dealing with such a complaint, as it didn't sound threatening, but of course, I wasn't there and couldn't judge it.
I can only speak as a teacher and mother. Yes you get frazzled in both situations. My children, I can put on the naughty step. I can remove a privilege. I can't do that with someone else's child.
I have taught both primary and secondary. In primary I had constant low level behaviour issues, like constant chat when I was leading an activity, children swearing in class, children making inappropriate comments that needed constant reminding to stop, people off task, and all day long. It just means that others can't learn if I'm always having to stop.
I know this wasn't mentioned by the op but when you've got small kids saying rude/odd things you do wonder where they learnt to speak that way. I read a lot of threads on mn where people are saying they don't mind their kids swearing. If it's alright for you if your 6 year old kid describes something as crap or shit, please think of the headache for me when they are passing that onto their peers. It becomes the tip of the iceberg, and as you go up the ages it does tend to lead to worse.
Of course there are going to be families for whom the above doesn't apply, but I do believe a lot is to be said for instilling respect into little ones from the start. I'm not condoning or criticising the specific wording of OPs complaint in this post, though upthread I probably made my position clear.
All theoretical now though as I don't teach anymore, in fact I homeschool.