They say int he post that they're doing optimized brute-force search, which honestly makes a lot of sense for the local-scaled context.

Vector databases are often over-optimized for getting results into papers (where the be-all-end-all measure is recall@latency benchmarking). Indexed search is very rigid - filtered search is a pain, and you're stuck with the metric you used for indexing.

At smaller data scales, you get a lot more flexibility, and shoving things into a indexed search mindlessly will lead to a lot of pain. Providing optimized flexible search at smaller scales is quite valuable, imo.