There's still a huge difference between "you can smuggle a null value in" and "the language can't statically reason about null values at all"

You can override TypeScript's checks for anything, not just nulls, and yet people still get tons of benefit from it. Same goes with many of Rust's safety checks in unsafe { } blocks.

Additionally, languages like C# and typescript have to be a little more flexible because they added this feature after the fact. Go had plenty of opportunity to do it up front and not require any compromises, and it chose not to.