Seeing Luke in person really wasn't much different then the internet. There was just something about him that John trusted. He wasn't big into the Star Wars fandom so he really didn't know much about him beyond his name and his lightsaber, but that didn't matter. It was the way he spoke that struck a cord with the doctor. He didn't have to worry about being so on guard around him like he did everyone else. Luke was a Jedi, and as far as John understood from what Jacen told him that meant he had to help people. Or he wanted to, and was a good listener.
It helped with his trust issues. John had had many people betray him in the past, trusting and letting in new people wasn't the easiest thing for him to do. Especially after suffering through heart break a second time around. He'd been promised a new life with Sherlock, a second chance like everyone else and it was soundly taken away. It'd driven him straight into the state of shock Luke saw before him in the man.
At the touch he seemed to relax, even as people scrambled by. John wasn't typically one for large crowds, but being around Luke he felt maybe he could try it. "Another day in my flat and I feel Rose was going to force me out and lose the key." He gave him a small smile, though the look in his eyes was still sad. It was a side effect that hadn't really faded since Sherlock's murder. "Suppose we ought to go experience it rather then just watch?" Despite himself, he was still unsure of crowds. Still looked at the market ahead with some hesitation.