I built Servo last week, I ran "git fetch upstream && git reset --hard upstream/master && git submodule update" and then "tokei .". So, unless Servo puts its cache in the dir, I would guess not, no.
I think by default servo does put the cache in the dir. So yeah, this would be an accurate estimate.
Though not all that rust code is written specifically for servo, and a lot of that C/++ code is winapi and skia. winapi is autogenerated, and skia isn't used by default anymore iirc.
https://gist.github.com/steveklabnik/b4ede6f13c9d609edc61d74...
(using a gist since the output is huge, and see Manish's comment as well)