Earlier today I read that Twit…X had threatened to sue and got quite an epic reply from CCDH lawyers which underlined the many ways in which a lawsuit would hurt X first and foremost. Apparently they decided to have a go anyway. Time to get some popcorn 🍿
If I remember correctly, it is explicitly referred during the time Dream is held captive by the Burgess family. It is explained that the universe tries to make up for Dreams absence and a guy sees nightmares that cease only when he starts wearing a gas mask and fighting crime. This is the pulp version of the Sandman, so yes, He is part of the Gaiman lore.