What do the Additional Resources say about Path of the Hellknight? That would be the most logical primary source for the Order of the Torrent.
It says nothing helpful, if I'm understanding the OP correctly.
Pathfinder Campaign Setting: Path of the HellknightAll material in this book is legal for play with the following exceptions. Conquering brands and branding iron are not legal for play. A PC may only benefit from either the Hellknight Obedience or a similar obedience character option (e.g. Deific Obedience) at a time, except as allowed by the Might of the Godclaw revelation. In order to swear allegiance to a Hellknight order for the purpose of qualifying for character options in this book, a PC must be lawful-aligned. The shackle spell uses either the fetters or frontal restraint rules on page 15.
If it doesn't say anything about the Order of the Torrent's order discipline choices in Path of the Hellknight, then the only source other than that would be Hell's Rebels 2, which is not sanctioned. Based on the AR, Order of the Torrent is legal, but you then have to reference an illegal source.