An Olympic Equestrian Rode a Horse in a ‘Mankini.’ Australia Loves Him.

When the Australian equestrian and three-time Olympic medalist Shane Rose mounted his horse for a costumed competition wearing only a G-string bikini, or “mankini,” he thought it was all in good — albeit somewhat uncomfortable — fun.

Mr. Rose, 50, wasn’t expecting to receive a call from Australia’s governing equestrian body notifying him that he was under investigation and temporarily barred from competing. But he did, and for a few days after the competition on Feb. 11, he feared that the episode might derail his preparations for the Paris Olympics.

On Monday, the body, Equestrian Australia, said it had cleared Mr. Rose of wrongdoing at the event. But in a country of unselfconscious beachgoers, where small, tight swimwear is a common sight even on prime ministers, the incident had already made national headlines and sparked a barrage of jokes and criticism of the investigation on social media. A few supporters even wore mankinis of their own in solidarity.

Matt Shirvington, a news presenter on Seven Network and a former Olympic runner, jokingly threatened in a television broadcast on Monday morning that if Mr. Rose wasn’t able to attend the Olympics because of his mankini, current and former Olympians would start wearing them too.

“We’ve got to take a stand here,” he said.

Mr. Rose, a horse trainer and equestrian from the town of Werombi in New South Wales, specializes in eventing, an equestrian sport that includes dressage, cross-country and show jumping. He won silver medals in the 2008 and 2020 Olympics, and bronze in 2016.