Their rationalization is that it is not listed on enough "recognized exchanges." I believe it needs to be on 5 major exchanges these days (They don't count Ionomy and other smaller exchanges.) They also bizarrely named it "Hive Blockchain" on the page (it's still in the URL) and excluded the DHF funds from being counted in market cap (90 million.)
I would recommend everyone on HIVE to support @coingecko and start using their site instead of CMC.