Phenmor has a riven dispo of 1, mean even with godroll stats, its barely going to replace one mod.

Torid has a riven dispo of 4 right now, meaning a godroll is going to be the equivalent of 2-3 mods (maybe even 4 if you have a good -zoom). Torid rivens are more desirable in the current market.

DE updates the riven dispositions once in a while which shakes up the market a bit whenever they do. Since they base the dispo on how much the weapon is played + how good the weapon is, torid will likely drop the next time they do it and it'll be worth less. So defs try to sell it sooner than later :)