"maybe", then you don't know if it is easier to write a rust naive compiler than a C naive compiler (look at tinycc, cproc/qbe, simple-cc/qbe, etc).

You don't seem to be asking a question anymore. That's not what I said maybe to, anyways. If both languages have grammars that are on the same level, I don't see why someone experienced in writing a lexer/parser would have more difficulty with one. I think Rust only needs lookahead for raw strings and there are some quirks with C's grammar, but I'm not knowledgeable about that.