What's the verdict on
this case, in which a mixer URL is used as part of an escrow contract?
Not allowed:
It's not allowed for mixers to do giveaways, sponsorships, bounties, paid posts, or paid ads in posts. If a thread is for paying people to do something for a mixer, then that's also not allowed.
The thread is strongly linked to someone being paid to do something for a mixer, and it's also an advertisement/paid-post.