He knows that software locks on cameras are not trustworthy. Everyone who wants to be certain that their laptop camera isn't watching them should do the same.
I always tape all of mine. Funny thing is, I don’t really care if someone gets a pic or vid of me jacking off. The microphone would be a much better way to get info of any value or to blackmail me. I never tried to tape off the mic, if I could even find it.
I'd like to point out that thanks to Signal, WhatsApp has end-to-end encryption. So Zuckerberg likely wouldn't be able to snoop the content of that message.
Use Signal if you want a more trustworthy replacement, it's great! If you want something even better but less stable, check out simplex.chat.
if you're a cool tech wizard use xmpp
if you're a fever dream use Briar
if you're from the future.. is secushare nice?