He was also shown being held up to the plane window by Mr. Galin, with Aeroflot’s branding clearly visible on the headrest.

Those images eventually played a role in his downfall.

The airline told Agence France-Presse that it opened an investigation after Mr. Galin’s post caught their attention, and that it eventually found video surveillance footage of the cat swap at check-in.

“Aeroflot has taken the decision to take this passenger out of its frequent flier program,” Aeroflot told the agency. “All of the miles collected during his time in the program will be annulled.” According to news reports, Mr. Galin had nearly 400,000 miles on his account.

Aeroflot did not respond to requests for comment. In a message, Mr. Galin confirmed that his frequent flier account had been blocked, and said he found out about the penalty through news reports.

The story of the cat swap became so widespread in Russia that it was even mentioned on Wednesday in a daily call between President Vladimir V. Putin and Russian journalists.

Mr. Putin said that the Kremlin did not comment about cats.

Mr. Galin justified his actions in his social media posts, saying that Viktor had become ill on the first leg of his trip, from Riga, Latvia, to Moscow.

Two days later, before the second flight, from Moscow to Vladivostok, a fastidious employee weighed Viktor and declared him too tubby to continue to fly in the cabin. Mr. Galin was then offered the chance to check the cat into the hold.