TBH I dont care which of those fights is the Main and which the Co-Main, but I do think from a logical point of view that the HWs should be main, and if you have read Sherdog over the last 18 months you would know that nearly everybody wanted Tom to fight for the HW title (yes, I know it was because most wanted him to beat JBJ) and that he was mentioned at least 5x more often than KC during this time.
I cannot remember that there was ever such a big Sherdog-Lobby for somebody to fight for the title as it was for Tom, so, why now change it to KC vs RDR? Why the sudden change of mind???
Tom vs Jones was hyped fight but not vs Gane and besides Tom is already the champ now.
KC vs RDR will be the main attraction and I don´t think the UFC will put KC vs RDR on co-main.