It kind of is, as is any other memory safe language.

You certainly can still write security vulnerabilities that don't involve memory safety violations, and these languages always have unsafe escape hatches that you can use to shoot yourself in the foot. But as long as you don't just sprinkle unsafe on everything, using a safer language is going to make a ton of vulnerabilities just disappear.

Looking at the issues from this past week, safe languages won't stop you from using 4 as your private key, but they would have entirely prevented the PHP vulnerability.