At one point the user linked to a rust-lang forum thread from 2016-2019 as evidence that Jai has "some of the tools to make the code language agnostic" or something like that. The thread started with a discussion of array-of-struct vs struct-of-array data layouts, which of course has nothing to do with making code "language agnostic." The user also mentioned the coding influencer lunduke multiple times. So I think they are simply misinformed on a lot of points, and I doubt they're in the closed beta for Jai.

(I read some of the comments simply because I had the same question you did. And, as it happens, the last post in the forum thread I mentioned was written by me, which was a funny surprise.)