Yoshi-P already said at the last Fanfest that Job Quests will not be structured the same as they were before. So you can easily fit whatever story you want into Red Mage's structure. Even if it was the same they can still make a workaround with it.

I have no idea why you would want to start at 30 instead of 50. Especially how 40-50 is easily the current most excruciating part of the leveling experience. Just go do a level capped dungeon or FATE if you want to learn the job at lv.30. Having RDM at 50 is one of their best decisions.