Agree, the claim "secure because Rust" is wrong. But "more secure than if it were written in an unsafe language" is probably going to be true most of the time.
Nah. You’re assuming that the developer has some experience. The false assurance that the magic of Rust will protect the developer from himself/herself will lead that young developer to make worse decisions. An experienced developer typically has discernment, and has learned, rather painfully, that he/she can make serious errors in any language.
No. Rust is excellent for beginner programmers dipping their toes into systems programming for the first time. Imagine you have a million-line C codebase, and a brand-new junior hire. Are you going to unleash them on the codebase unsupervised? Hell no, you're going to need to watch them like a hawk and regularly slap their fingers in order to teach them what not to do. But I would gladly unleash a junior on a million-line Rust codebase, as long as I have a CI rule that flags any PRs that touches files containing the `unsafe` keyword. This frees up the junior to spend more time learning the business domain and less time worrying about bizarre memory errors.