You may not have been around to experience it first-hand, but we heard a lot of claims made back in the 1990s about how Java and the JVM would increase security and safety.
The arguments made then even overlap with some of those being made in this case! The lack of direct pointer access and manipulation, automated memory management and better bounds checking are some examples of the arguments used then and now.
Yet if you work with computers at all, I'm sure you'd know that many of those claims did not materialize. Flaws have been found in the various implementations of Java and its VM, and these have affected its security and safety in very serious and significant ways, many times over.
Perhaps things are different in the case of Swift. But we won't be able to say for sure until later on, once it has undergone some significant real-world use.