All the
Relative scales of A Major would "work" because they are the same notes: A Ionian, B Dorian, C# Phrygian, etc., even though A is the tonal center, which makes it Ionian Mode.
Parallel scales (A Dorian, A Phrygian, A Lydian, etc) won't work. They are from different keys.
Griff's course is written in G Major. All of the example solos are written in
Relative modes of G Major and use the notes and chords of the G Major Scale: G A B C D E F#----> G Am Bm C D Em.
In each solo example, the tonal center (I chord) will be a different chord from the key of G Major.
Griff will encourage you to play each of the 7 Standard 2 Octave "boxes" over each of the Jam tracks for the 6 modes since you are actually always playing the same 7 notes.
The chords determine the mode, not the scale or "box".
Since your track of "The Weight" progression is centered on the I chord of the Key of A it's in A Ionian, regardless of what scale you choose to solo over it. (A Major Pentatonic, maybe?)
Those that prefer playing "The Weight" in G will still be in Ionian mode.
Is everybody happy?