Well you are correct about G9. I seem to be labouring the seventh. Research shows I need not mention it as G9 always includes a seventh which is exactly your point.
This is from Wikipedia:
There is a difference between a major ninth chord and a dominant ninth chord. A dominant ninth is a dominant chord (and minor seventh) with a major ninth. A major ninth chord (e.g., Cmaj9), as an extended chord, adds the major seventh along with the ninth to the major triad. Thus, a Cmaj9 consists of C E G B and D. When the symbol "9" is not preceded by the word "major" or "maj" (e.g., C9), the chord is a dominant ninth. That is, the implied seventh chord is a dominant seventh, i.e. a major triad plus the minor seventh, to which the ninth is added: e.g., a C9 consists of C, E, G, B♭ and D.
However, without the third, the GDFA chord is not a true G9 is it? If so, it returns us to the G7sus2 description. I was hoping someone would say the voicing will help determine the name of the chord. If voicing modifies the chord function, it would modify the chord name. To me, G9 would be better than G sus2 because the A, placed an octave above the root, functions more as a melody note than as a sus2 harmonic dissonance. Am I right or wrong?