The Presidential Security Service has done it again. It looks worse this time, and they should come up with a better response to hecklers -- because there will be more.

It happened when President Yoon Suk Yeol was giving a speech at the graduation ceremony of the Korea Advanced Institute of Science & Technology in Daejeon on Friday. A man in a graduation cap and gown stood up from the audience and began yelling that Yoon should restore the state budget for research and development, which the government cut for the first time in 33 years.

According to the PSS, its agents told him to stop and sit down, but he continued. Then, photos and video footage show, an agent covered the shouting man’s mouth with his hand and others joined to carry him out of the indoor venue.

The man, a KAIST graduate named Shin Min-ki, turned out to be a spokesperson for the Daejeon branch of the minor opposition Justice Party. He was dozens of meters away from Yoon, unlike Rep. Kang Sung-hee of the minor Jinbo Party, who held on to the president’s hands seconds before he was muffled and taken out by PSS agents on Jan. 18.

The presidential office told reporters that Kang did not let go of Yoon’s hand and even pulled it toward himself and that the PSS took action according to security protocol.

This time, there was only shouting from a distance. Yoon’s office said the PSS “removed a disruptor for safety in the heightened security area, and to maintain order within the event venue,” and again, that it was “an unavoidable measure in compliance with security protocol.”

Shin said in a press conference on Monday that he was "locked up" in a place within the KAIST campus for 30 minutes, and moved to a nearby police station. Police are set to question him again two weeks later over a suspected "interference of business."

What is most disturbing is the PSS officials’ repeated clasping of their hands over a protesting person’s mouth. One can be moved out of a venue if he disrupts an event, as per the manual, but is the forceful hushing really necessary?

South Korea is a democratic society that shares its core values with its strongest ally -- the US. The two allies have endlessly emphasized that their ironclad alliance is “rooted in common democratic values and respect for human rights.”

The US Secret Service and police take action to protect such VIPs at the slightest sign of a security risk, but they do not cover a speaking person’s mouth.

One of the best-known cases of use of excessive force in the US took place in 2007 at the University of Florida. Video footage shows police officers escorting out a student after he heckled then-US Sen. John Kerry during a forum at the school. They did not cover his mouth even as he yelled and aggressively resisted for two minutes, although they eventually drive-stunned him with a Taser after multiple warnings. Disruptors at US campaign rallies or other political events are often escorted out as they keep protesting, but they are not muffled.

The PSS said they employed a technique called “igyeoksul,” which includes covering the disruptor’s mouth, to separate the “potential threat” from the president.

During Yoon‘s prerecorded chat with a KBS anchor that was televised earlier this month, Yoon said he wished to be remembered as “a president who treasured children and prepared for the future through the advancement of science and technology.”

Many children would be appalled to see photos of PSS agents violently shushing someone graduating from a top science university, then repeatedly hearing that the PSS has done nothing wrong. They might even get the wrong idea that they should keep their mouths shut at all times, like children in China or Russia.

Similar incidents will continue to happen. Will Yoon decide not to attend these events? Will the PSS continue to act like someone’s speech can be a threat to the president? They cannot, and they must not.

It may be unrealistic to expect the president to gracefully address hecklers during speeches like former US President Barack Obama did, but the least he can do is to ask the PSS to stop gagging people.