The 3x3 average IS all that matters.
Whether this guy's solve is legit or not shouldn't affect your opinion on the validity of cubing. You should come across the fact that easy scrambles, and EXTREMELY easy scrambles happen, that's why people put L single and NL single when they are posting their PBs. There have been hundreds of competitions with thousands of competitors, it is irrational to think that something like this couldn't actually happen through pure chance of truly random scrambles. Although I personally agree that it is fake, my point is that this will almost certainly happen again and be legitimate by a sub-10 solver that most people aren't as familiar with as they would be faz or 5BLD or valk. And there will be speculation, and there will be suspicion, and there will be haters and disbelievers, but it will ultimately be proven legit. Or not be proven, but either way it will happen and be approved by the WCA board. However, that is his LUCKY single, he still has 4 more solves to do, and unless he gets 4 more EXTREMELY lucky solves, his average will reflect his skill much more accurately. And since the best and worst times are omitted and the remaining 3 become mo3, his L single isn't even factored into the average.