In Andrew Garfield's defence, he was trying to joke around with the kid who was just a little too shocked to see him to respond.
Speaking to The Guardian about his latest appearance in Silence and his time in the spotlight as Spider-Man, Garfield told a brief story about a time a young fan started filming him as he played basketball in New York:
I was horrible and sweaty. I thought to myself, "I'm not very good at basketball, I don't really want that." See? The ego crept in. I started running towards him like I was going to tackle him, just joking around with him. But he's not moving. He was just looking at the screen, slack-jawed. Until I'm right in front of him. I said, "Hello!" and he pulled the phone down for a second and freaked out. It was so dissociative. I was scared for him. I could have been a really bad dude and I could have hurt him. I mean, go and climb a tree!
I am not sure I would have understood what was happening if someone famous started running at me, either. Especially when I was seven. I'm also fairly certain that, had it not been a famous person, the kid would have run.
That said, the experience could have reinforced the idea that Garfield had when he took the role. Earlier in the interview, Garfield talks about his goals and, man, does it sound like it would be impossible to get out of your head and just act with all this in there:
I'd been reading the mythologists Joseph Campbell and James Hillman. And when I took on Spider-Man, I thought, "Holy shit! This is exquisite and terrifying and incredible. I have been given the responsibility of reaching my hand out from the big screen and putting it on [young boys'] shoulders. That is a gift for me and a big burden to carry. And I'm so up for it."
I thought, if I can infuse all this ancient knowledge and wisdom into [Spider-Man], it could be profoundly affecting for young people in the audience. That was always my intention and what I tried to do.
Affecting enough for them to film him on a basketball court? Sure. That seems about right, even if Garfield thinks the kid should have run from him.