Is it? The sign falling down was a humourous moment, especially given the context of the discussion. The producers seem keen to leave in people messing up - hence Sam's lights going out (yes, it's his fault for playing with silly power supplies, but you get the point), the man from Hornby breaking the model he was supposed to be fixing, Waterman's layout not fitting together properly, issues with the water on Heaton Lodge Junction, etc. I think its important to include all of this to show that we all make mistakes, and it's part of the programme's effort to show off as much of the hobby as possible - something which has been widely praised on here. As somebody who's doing trying things for the first time he's bound to have some failures. Leaving them in the programme is important for other new modellers, especially younger ones. Being young he's somebody that they might connect with a little more easily than yet another old man with grey (if any) hair, and he's building very good layouts. But just like them, he's still learning and things don't always go to plan - at which point he doesn't give up but tries something else instead. And ultimately, it all comes together to produce a brilliant result.
I'm less than a year older than him, and pretty much every part of that segment I empathised with. Plus, I would be thrilled if I had half the confidence he must do to have put himself out there like this, or could produce a layout half (or even a quarter) as good as his.