You more or less said that the grandparent was wrong "just because." You were telling someone that he was wrong without any argument. Exactly what you complained about with me, btw.
The only possible response to that sort of thing is snark.
The only possible response to that sort of thing is snark.
Uh.. no it's not. You could respond like you just did now and explain that they "were telling someone that he was wrong without any argument."