I'm with you quinzinho and will be establising and linking accounts for DW who isn't a Primary.
The problem here is that it is very open to interpretation. I think it is like that missing bullet in another T+C a while back.
Per the different instructions sent to me and DW : GET (her as secondary cardholder) or HOLD (me as primary) premium card as the primary cardholder were listed as one of the 5 options of which you had to do 3. Plus it was the last one in the line which is rarely the most pivotal.
All the other promos have been very upfront about being for cardholders. The Primary cardholder distinction was always lower down in the T+C also.
AE marketing are pretty good at what they do I think. If this was about making people get a card, they wouldn't hide it.
More gain to AE to entice you into a premium CC than to mislead you into linking Uber or Starbucks for a couple of months and then getting out on a technicality and eroding loyalty at the same time.

It just occurred to me, this site needs betting chips. Earn them like Priority rewards for posts, then whenever these debates happen you have to bet one. If you lose all your chips, you can't make predictions until you earn another.
I'm going all in that Primary cardholder refers only to activity 5, not eligibility. I will accept my gold bracelet as an NFT