Wait a minute...is this a plot-hole (Austerities of Wind and Main Scenario-related)?

[Riepah]

Don't forget the biggest hint the game gives you: you can only summon a primal you were there to defeat.

Exception being Bahamut come Heavensward, apparently.

[Rocl]

Exception being Bahamut come Heavensward, apparently.

Let's not count our chocobos before they've hatched! There's ways they can reconcile it come Heavensward, so calling an exception so soon is hasty at best. (The easiest being the SMN storyline might have you fight a weaker version of Bahamut or some such nonsense [I hope not]; the more complicated being some Allag-related explanation regarding their ability to summon Egis and their enslavement of dragons)

[RomildaRayne]

Exception being Bahamut come Heavensward, apparently.

By the time period of Heavensward, the Warrior of Light has already cleared the Final Coil of Bahamut; it's part of the story, even if not a mandatory one for each and every player.

Don't be surprised if the game acts as through you've defeated the Coil storyline regardless of whether or not you actually did; World of Warcraft does the same because it's easier and more sensible not to make the effects of raids only available to the raiders able to complete it and it's very rare that completing a raid will make a difference in how people treat your character.

[Kaiser-Ace]

By the time period of Heavensward, the Warrior of Light has already cleared the Final Coil of Bahamut; it's part of the story, even if not a mandatory one for each and every player.

Don't be surprised if the game acts as through you've defeated the Coil storyline regardless of whether or not you actually did; World of Warcraft does the same because it's easier and more sensible not to make the effects of raids only available to the raiders able to complete it and it's very rare that completing a raid will make a difference in how people treat your character.

Since there were i think 3 or 4 others in the "Hydaelyn's Crystal" CS at level 15 I'm assuming that there's the usual 4-5 WoLs that usually appear in final fantasy. So it wouldn't be out of the question that One of the Warriors was Canonically responsible for stopping Bahamut, While another was felling the EX primals, while a Third Was exploring Crystal Tower, all while Deprplander was clearing the Main Story's events. Thus giving use a little more flexibility with the plot.

[Alberel]

Exception being Bahamut come Heavensward, apparently.

There's meant to be a fair bit of story pertaining to Bahamut in Heavensward so it's entirely possible players that haven't cleared Final Coil will be exposed to his aether in some other way.