TFA really overstates the importance of the part in question. The part is typically is plastic, and serves primarily an aerodynamic function, improving fuel mileage, with a secondary function protecting the engine bay and limiting ingress of dust and debris. It’s really not a critical part and typically replacing every bolt with a zip tie of sufficient size (that is important) would be enough to hold it in place. It is indeed quite common for the bolts to be replaced with zip ties; often the bolts are weird shapes and sizes and threading. In fact, several cars I’ve worked on have used plastic screws which wouldn’t have significantly greater strength than a zip tie.
But in this car it’s metal, which makes me wonder if it’s a semi-structural component and therefore the zip ties wouldn’t hold, though this is again a pretty uncommon configuration outside of convertibles (which need reinforcement as they lose the roof structure). The photo in TFA shows some very thin sheet metal, and I don’t think that it is structural in any way.
In any case, if a shield falls off your car and it makes you drive into a ditch, particularly after you’re made aware there is a problem, I’m not sure you’re really prepared to safely operate a 1500kg wheeled vehicle at 100kph.