> what programming language was best for their situation, which was removing the Rust language and using something else

This is correct, but I'd say that the key was removing Rust and not using something else. Fewer moving parts, fewer JS runtime boundaries to cross, no need to make certain that the GC won't interfere, etc.

Also, basically any rewrite is a chance to drop entrenched decisions that proved to be not as great. Rewriting a large enough part of Prisma likely allowed to address quite a few pieces of tech debt which were not comfortable to address in small incremental changes. Consider "Prisma requires ~98% fewer types to evaluate a schema. Prisma requires ~45% fewer types for query evaluation.": this mush have required quite a bit of rework of the whole thing. Removing Rust in the process was likely almost a footnote.