Not that it matters, but I think it's much more likely he chose Rust specifically for the language features over Go. A lot of Rust's type-system and semantics are inspired by ML-family languages which are well-known to be great for writing parsers, etc.

At the initial presentation, Ryan mentioned that a move from Go to Rust was a possibility due to a few things, and they were related to the languages themselves, not to Mozilla vs Google or something.

(And, IMHO, saying that Rust is a Mozilla thing is just plain incorrect.)