You don’t need to be an experienced spy as Black Water to understand that anyone with even a bit of pride and self-esteem would feel severely annoyed and offended by such an attitude which Slytherins have demonstrated, especially such a hot-tempered personality as Ron Weasley, who has already freed from McGonagall’s spell and wanted to expressively share his disagreement with the only reachable audience – the former ghost himself and his not-really-brother.