The use case is quite simple. Most data-oriented applications where you need linear algebra, probability theory, statistics do contain a significant amount of data pre-processing and business logic once extended to enter production. Here static typing is advantageous. Keeping the whole codebase in the same language is a significant advantage.
Furthemore, some statically typed languages do have typing features that are advantageous for data analysis. Think F# type providers or type systems where e.g. the shape of arrays is guaranteed to match at compile time.
The question is whether Rust is a good language for this, or we need something more like OCaml or F#. All these languages pop up in job offers for quantitative analysis, insurance risk modeling, etc. So there seems to be a demand.