It really was a testament to how far both of them had come that Declan wasn't getting mad due to a misinterpreted comment from Arthur, and that Arthur wasn't unintentionally goading Declan into an altercation. That in itself was reassuring.
Despite his own feelings at this unexpected development, Arthur forced himself to steady his voice as he continued. "It isn't the Muggles themselves that concern me," he admitted, glancing around to make sure nobody was close enough to hear his words. "I've never been here before. I don't have any idea what anything is. I don't have any money. I—"
Forcing himself to inhale deeply, Arthur took a few moments to centre himself. When he looked at Declan again, he felt his head shake slightly. "The sentiment of privacy is appreciated," he said, not wanting their conversation to devolve into a dispute. "But I wasn't expecting this, so you'll have to forgive my indignation."