Many thought Trump made a mistake in agreeing to meeting chubby Kim. That would greatly elevate Kim, yet there was never any real hope of NK actually giving up its nukes.
NK would have gotten far more from such a meeting, able to flaunt their new status as an ‘equal power’ to the US; while Trump would have been roasted back home afterwards for achieving nothing with the summit.
So all this seemed almost like a deliberate and concerted effort by the Trump team to sabotage the meeting so Trump doesn’t have to admit he made a mistake in agreeing to the meeting in the first place.
While this might help Trump with damage limitations domestically, the South Koreans are going to be pissed at being so forcefully reminded that they don’t even have a seat at the table that decides their most fundamental national interests.
Many more such demonstrations and the South Korean leadership might actually grow a pair and start thinking about actually taking control of their own destiny.