Its so obvious to me that Overeem is using words to get a title match sooner rather than remaining quiet and waiting till the winner of Cain/JDS. If a fighter falls for trash talk, then by all means, use whatever tools to get the fight.
For the most part, I take trash talk from any fighter with a grain of salt.
I'm not sure it's even that, he may be toeing the company line.
Who would the UFC rather see in that cage across from JDS, Reem or Cain? It's not like Overeem has to convince them, or that JDS has any actual say on the matter.
It's just fight promotion, IMO.