No, it’s not a rude gesture.
Here are two large pink birds from a few years ago in Melbourne. The occasion was a visit to the Victorian Hot Rod Show but these enthusiasts were down at the Federation Square museum on Flinders Street the next day having a display all their own.
The pure sports car enthusiasts will sniff and the continental touring car trendies will snort, but unless you are an ear nose and throat surgeon you need not listen to them; Ford Thunderbirds are an entire class of car to themselves. They started out as the American personal car, then almost made a competition with the Chevrolet Corvette as a sporting car, and then went on their own way as a luxury cruiser.
As with all creatures they got bigger and wider and heavier as time went on – but modern redesign stepped in eventually and toned it down. Unfortunately a revival of the marque failed after about 4 years and the name is currently shelved.
I can only hope that it will return.