To give another perspective of CT’s mindset -
CT is not against people paying the promo price as they are clearly paying to advertise it (though they likely want to limit the promo exposure to an extent). But as a company with big marketing spend they need to track the source of traffic and profitability at the channel level. When DDMS posts an embedded link or tells people to google to find the deal, it messes up their internal metrics completely.
It makes sense to turn off the ad promo and offer a code that is meant for deal sites.