Serious question: why would more visibility keep it safer? Israel continues to commit far worse crimes against humanity, very openly, on a daily basis. Why would this be any different?
Because there is a point of no return in the worlds perception of you, the U.S. has been protecting Israel from that, but every time someone asks difficult questions of Israel and isn't silenced or hurt the powers of fascism lose respect from other evil people because they look weak.
More eyes on Greta means Israel has to make a choice it doesn't want to, de-escalate. The IDF is trained in committing genocide with military weapons, they are utterly untrained in fighting an actual war at this point, they really have very little leverage to continue the genocide of palestinians now, though of course "too little too late" is the necessary refrain.