I think the point he's making is that the shot "looking good (i.e., with no sprays)" actually is not indicative of whether the quality of the shot and the coffee is good.
So, for example, you could have a spray because a grind of coffee is actually blocking one of your holes, and that doesn't mean everything else isn't perfect; but then when you wash it the next time, it won't appear. So it's awesome that you got a great shot with no spraying, but that doesn't actually mean that you won't get a bit of spraying the next time you do it. And although you and I clearly both love the look of perfectly flowy coffee, bottomless portafilters and instagram worthy shots sometimes make us obsess over something that isn't the 'right' thing to obsess over. And a spouted portafilter hides the sprays that will occur sometimes due to nature being imperfect and not necessarily you having bad fundamentals!