Dude, was the kid armed? Because as much as I despise Kerry, I'll give him credit for one VC dead. The VC might have "recruited" children, I've heard of our soldiers fighting against children in Somalia and Iraq. It's nasty as all hell, but the moment you pick up a weapon and point it or fire it at our guys, expect to get ventilated. My understanding is that your protected status as a civilian is not protected any longer the moment you decide (or are forced to) pick up a weapon.
Is it deserving of a Silver Star? Well, jeez, that's an awful important award for picking off a wounded VC with a rocket launcher. Rocket lauchers can kill your crew if they hit the boat, but I'm unaware that doing your job got you special commendation. Seems kind of a reach. Beaching the boat would seem counter-intuitive, as then it is a perfect sitting target. A fast moving boat would seem safer than one you beach with respect to rockets. I wasn't there, I don't know how swift boats operated (what the procedure was when you came under rocket attack). I'll defer to the actual vets themselves. What do they say?
I call that murder. You're free to call it whatever you'd like. And doing so hardly makes him a hero.