I don't think the article is suggesting people actually literally followed that dotted arc - the mountaineering trust chap's quote is that all the routes from that car park are trepidatious even for experienced people.
i.e. their concern is that GMaps users are being directed to that car park, (the highest one, hence closest to 'Ben Nevis' marker) not what the dotted line does or doesn't show from there on. So the solution is to direct them to the (lower-down/further away from destination) visitors' centre car park instead.
> Mountaineering groups said the dotted line crossed "potentially fatal" steep, rocky and pathless terrain, while a suggested walking route for a different mountain, An Teallach, would lead people over a cliff.
i.e. you can wiggle it all you want, it's what it crosses that's the problem, you'd have to walk around and go up a different face?
i.e. their concern is that GMaps users are being directed to that car park, (the highest one, hence closest to 'Ben Nevis' marker) not what the dotted line does or doesn't show from there on. So the solution is to direct them to the (lower-down/further away from destination) visitors' centre car park instead.