Well, the first 500-ish lines of that 1500-line file are comments, and there are block comments throughout, too...
You did, to be fair, say that comments at the top shouldn't count. But I think that depends a lot on personal (and language) style towards multiple files and multiple units within a file - for instance, none of this code is object-oriented, and comments above each class make sense in an object-oriented language. I think as the language gets more concise - Go is a lot more concise than the Apollo assembly language - you're going to need to have the same amount of prose to explain what you're doing but a lot fewer lines of code to get anything done, and it makes sense to have comments above each function or each block, because that's really the comparable unit.