Would a 1978 kid really be that out of touch by 1986?
I know they threw in obvious differences for comedic effect and to show how things had changed from his perspective and made him feel displaced. But when you really get down to it, alot of what was cool by the mid 80s was already in its early stages by '78. When he's talking to the chick who came into his room (she was probably about his real age too), you'd think he was a kid out of the 60s or something, lol.
"80s bands"/singers like Foreigner, Tom Petty, Journey, The Police, Eddie Money, Blondie, and Van Halen already had their first hits by 1978. I believe that was when they started making the first music videos too (even if there wasn't much of an outlet for them before MTV), so it's a little hard to believe David would be so weirded out by a new wave video. At least the more cutting edge expensive TVs, I believe, already had remotes by then too. Punk rockers were already dying their hair then!
P.S. I admit the TV in David's room at the lab WAS a really good high-tech looking TV for '86 though! In fact, it doesn't look too different to the more recent gray/silver tube TVs of the 00s, with the speakers on the sides.