The CM never imposed to avoid posting in MegaSpam thread but rather not counting it as paid post so everyone is free to post on any topic here just like what Yahoo said.
Youre right. I remember also @tranthidung suggested to BC to allow maybe at least 10% of the total post can be on spam/mega thread. But that's it. More than that could really affect their interest for the campaign. The solution is easy, make a 25 post as requirement for their campaign and have some extra for those sections you love to post. I think that would be a good way to please everyone for those who really love big section with more than 100 pages of post.
Bestchange I guess have learned and still trying to find ways to make use of their spending.
Their spending a lot of money, I guess its not bad to make it worthy right. Every business could have the same point. Also bestchange is not related to gambling sites, so there is really a chance that they will limit post on that section.