Well, no two words have exactly the same meaning. So for example, if he said 'bullshit' that would have had a slightly different maning that 'horseshit'. And if he had said 'dogshit', that would also have a different meaning. Now if he said 'nonsense' or if he said 'baloney' either of those would have slightly different meanings too. But he chose to say 'horseshit' because that was, in his judgement, the perfect word to describe what he thought about your statement.
He acknowledges that he intentionally used harsh words.
So his intentions are clear.
Obviously he admits he can't have a dialogue in a respectful manner.