Marx and other passengers reportedly intervened when the man began pushing the flight attendants and pulling their hair, Marx wrote on Facebook.
And while Marx and his wife, '90s MTV VJ Daisy Fuentes, put the airline on blast for its response to the situation, Korean Air defended its handling of the ordeal, saying proper protocols were followed.
Fuentes posted on social media several photos from what she said was a four-hour ordeal.
The crew was "completely ill-prepared and untrained" for the situation, Marx wrote on Facebook.
The flight attendants didn't know how to use their Taser, and never fully gained control of the passenger sitting a row in front of the celebrity couple, according to Fuentes' Instagram post.
The man broke free of the rope tied around his hands three times, Fuentes wrote.
Seoul police boarded the plane when it landed at Incheon International Airport.
"Korean Air should be sanctioned for not knowing how to handle a situation like this without passenger interference," Marx wrote.
In a statement, Korean Air said its flight attendants followed "response protocol" in subduing the passenger with ropes. Flight attendants did not deploy the Taser, the airline said, because "the unruly passenger was moving around and there were other passengers near him."
"The flight attendant considered the safety of the other passengers and decided to restrain the passenger with ropes," the statement concluded. It makes no mention of Marx or other passengers subduing the unruly man.
Despite the debacle, Marx eased the concern of his fans upon landing safely in Seoul.
"Daisy and I are home safe and sound. No big 'hero' move at all. Just did what I would hope anyone would do in same situation. Tnx 4 concern," Marx tweeted.
Marx and Fuentes were traveling home to Los Angeles after vacationing in Vietnam. They also captured some of the more relaxing moments of their trip on social media.