The SQL syntax highlighting doesn't understand an unqualified JOIN keyword:
SELECT a FROM foo JOIN bar ON foo.a = bar.bOn most DBMSs, "JOIN" is an alias for "INNER JOIN".
I've made a few changes to the SQL syntax file. Give me a minute and I'll push to Github for you.
Here are my current changes.
I've compared your SQL.tmLanguage with Sublime's "pristine" one and the only difference is a few added functions, nothing related to the JOIN keyword. Are you sure you uploaded the lastest revision of this file?
Sorry, my test file only used "LEFT JOIN".