Is it against the ToC to sell carries?

[Delsus]

And that's why I started this thread, to ask the devs if there is any risk in selling these runs.

As people have said, mercing is not against ToS, but you could end up carrying players who have bought gil, whilst not your fault because you can't know where the gil came from, SE has it in their power to track and remove gil obtained from rmt.