The speedrun isn't for the entire game's completion, it's for the 2.0-2.5 patches, aka the timer finishes as soon as your control of your character is released (ala cinematic) and once it's released, the content you have to do from there on is stuff in Heavensward.

Another leaderboard can fall under for creation to 3.0, but I feel like since the current unofficial speedrun is 15 hours, we can start from there for our little community of this MMO's speedrunning. :D

Stormblood isn't finished, so we can't use that to completion, but instead to a certain completion of a patch point.

The image above from is from here. https://ffxiv.consolegameswiki.com/wiki/Main_Scenario_Quests It's to explain how that'l work. It would be similar to Stormblood, the timer would stop at the latest (or predetermined) patch in the same way.