Definitely a deserved member for this gambling company's campaign as this person is having 1 gambling post in their last 20 posts and that also talking about locking a topic.
Posting naturally in gambling boards if the campaign is for a gambling service.
You forgot to include this:
I select a few based on what I think would fit best for the campaign which includes but is not limited to:
Posting naturally in gambling boards if the campaign is for a gambling service.
Posting actively if the campaign has a higher posting requirement.
Account seem to be in good standing with the community.
My Addition: Ultimately, I do not owe you an explanation for whoever I decide to choose
If you're concerned about the selection process and you're convinced you'd do a better job than the CM, why not send your complaints and proposal to the campaign owners, they'd would be convinced to hire you.
OR
Why not post with your main account which probably wasn't selected,
again, let the community help decide if you're more deserving applicant, and If yes DT Members will revoke the manager's decision, fair ?