The suggestion adds nothing at all.
The hypothetical situation is: combat has just ended, and there is another fight less than 10 seconds away, so I want to be able to hit placate to start combat Hidden. But if combat is less than 10 seconds away, you can just target an enemy and hit Placate, thereby making you Hidden.
THE POWER ALREADY WORKS THE WAY YOU WANT IT TO, IT JUST REQUIRES A TARGET. IN THE SITUATION WHERE THERE IS NO TARGET, COMBAT IS MORE THAN 10 SECONDS AWAY.
The hypothetical situation does not exist. The change is not needed.