I think you have those backwards. Concise is expressing an idea in less words, expressiveness is the breadth of ideas that can be communicated. Go is not concise and does not try to be.
Just to play devil's advocate (in case this is what they were thinking), go's language definition is fairly concise, by design. Few keywords, little magic, leading to lower expressiveness per LoC.
When talking about lines of code written, "concise" is roughly "idea/length" whereas "expressiveness" is "sum of ideas", so yes, "concise" could be roughly seen as "expressiveness / LoC", but it's still the wrong word to use, as "expressiveness" specifically refers to the "breadth of ideas that can be represented and communicated". And either way, while the language spec is concise, the language itself is most definitely not
Go is a concise language but it's not expressive - you'll write 4 lines to call a func and check an error.
This means that PRs are inevitably going to be larger than a language like Ruby or other languages with metaprogramming.