The bit that image quoted was specifically for gate upgrades.

Priority Airport Upgrades:
If you’re a Cardmember with Aeroplan EliteTM Status, you and up to eight companions travelling on the same reservation get higher priority when you’re on standby for an upgrade on Air Canada flights. Should a seat become available, you will be assigned to it before Aeroplan members who have the same status but don’t hold an American Express Aeroplan Reserve Card. .. A Basic Cardmember or Supplementary Cardmember, and up to eight (8) other passengers traveling on the same reservation (up to a maximum of nine (9) travellers), are each entitled to Priority Airport Standby, and a higher priority for upgrade requests to a premium cabin.

Of course, "higher" is a relative term, and they don't define "higher than what" when using it. Blah.
They have a separate section/wording (almost identical) for standby.