I agree it's an "absurd counterexample". That's the whole point of a reductio ad absurdum. It shows the fallacy at the core of the argument with which you whole heartedly agreed. Precision is important in ethics.
Furthermore, even if I were to be maximally charitable in interpreting the argument as "damaging a person is typically morally more serious than damaging an object, and psychologically damaging a person is typically worse than physically damaging an object", not everyone would even agree with that, contra your post. I don't think you appreciate how broad ethics is as a topic; virtue ethics and deontological ethics both dispute the premises from which this argument is constructed.
Finally, discrediting an argument you agreed with does not somehow discredit or insult you as a person, so not sure where you got that from.
Furthermore, even if I were to be maximally charitable in interpreting the argument as "damaging a person is typically morally more serious than damaging an object, and psychologically damaging a person is typically worse than physically damaging an object", not everyone would even agree with that, contra your post. I don't think you appreciate how broad ethics is as a topic; virtue ethics and deontological ethics both dispute the premises from which this argument is constructed.
Finally, discrediting an argument you agreed with does not somehow discredit or insult you as a person, so not sure where you got that from.