I think they just accepted that advertisement to be put in their website. Everyone has to make money in someway, And I see that when you click advertising link:
What is the approximate budget for the advertising campaign? ($10000 minimum order)
But I haven't seen any policy about advertising scam ICO or projects.
So if anyone can afford to pay that amount they are definitely going to advertisement it on their website. I don't know who run coinmarketcap though, if it still own by CoinTelegraph. They also have a thread here:
https://bitcointalk.org/index.php?topic=199685.0