It really was hard to keep quiet when they were offering so many perfect opportunity to insult them, not that the house itself wasn't an insult. Humble indeed, right in the middle of no where, in a Muggle area. The only reason you'd want to be in a Muggle area was if you were close to something. However, while he could refrain from insulting the house, he couldn't listen to the Mudblood make fun of his brother.
"My brother would have no way to determine if any news you wished to disclose could be shared in an owl unless you told him such news. However, I do understand that logic isn't always appreciated by most," he said. "Sirius is a Black; ergo he does not need to be trained by anyone."
Regulus tilted his head. "Were you hexed in your hearing? I'm sure that James stated that it's from all of us. He didn't bring it, but I have no preferences on the matter."