I'm not really sure how you could wedge SQL into a system that doesn't really have the concept of columns without it being, at the least, a distinctly different dialect.

And, really, if you've worked with some of the "higher level" interfaces to SQL like SQLAlchemy or Laravel's QueryBuilder, ReQL doesn't seem that alien; they all tend to work by method chaining as well. (But they usually don't support everything SQL does, unlike ReQL's interfaces.)

Also: unlike my (admittedly limited) exposure to other NoSQL systems, RethinkDB supports relations and joins -- it's actually a lot easier for an SQL fiend to move to Rethink than any of its competitors.