A suggestion for how to clarify Primary Target vs grenades next errata
Change "Before you make an area attack with a weapon (such as from the Area-Fire or Auto-Fire actions,[...]" to "Before making an area attack with an area weapon (such as from the Area-Fire or Auto-Fire actions, with a weapon that has either the Area or Automatic trait),[...]"
As grenades themselves don't have the Area(Burst) trait, but rather give you a special single-action with that trait, they are exempted from Primary Target but still included in Suppressing Fire. Grenades are Thrown, Consumable weapons that give access to a special version of the Area-Fire action.
This would, to me, as a soldier player, satisfyingly clarify Rules As Written that grenades are not included in primary target. I get they were not intended to be included in the first place but the language was just vague enough that i got my hopes up in the first place.
As of this writing the Primary Target feature does not require the weapon you are area attacking with to itself have the area or automatic trait. I get the intention with the current balancing of grenades that they were not to be included, because at higher levels you'd be competing with blaster casters for direct damage. However, intentions aside, someone missed that the current wording of primary target did not actually exclude grenades. (unless they meant that a special Area-Fire action did not count as Area-Fire because it's not the standard Area-Fire in which case.... why?)
It's fine, we're all fallible, people miss things, it's fixable, and should be included in the errata and not the faq. FAQ might clarify intention, errata actually fixes the rules.