From Fiveouncesofpain:

Frank Shamrock and I have verbally agreed to fight each other, but from what I understand he’s being difficult in the negotiations. For whatever reason he may have, I think it’s too bad because I think it’s the type of fight that would draw a lot of attention. It would be two guys that were UFC champions and have done a lot for that organization, and now they’re involved with Strikeforce. I think it just made sense. But for whatever reason I think he’s having trouble pulling the trigger. He may be nervous about getting slapped around, but that’s the way it sits right now. Hopefully I can find someone else to fight if he doesn’t want to do it. I want to get in there before Summer.

He thinks it made sense for who and would draw a lot of attention from who?  The only way this fight would generate any interest whatsoever is if it took place in San Jose.  Shamrock's drawing power is holding on via dental floss there as he's lost his last two via devastating fashion to Nick Diaz and Cung Le.  These are the type of fights that Strikeforce needs to avoid putting on.  Sure, the UFC is using two older guys as the main event of UFC 109.  However, Couture has more drawing power than both these guys, and well the UFC can afford to put on a fight like this.  That doesn't make it 'right', but they have more leeway due to brand name recognition, etc.  I guess Coker and company really do see themselves as the second coming of PRIDE with all these useless and last minute fights they are beginning to put on.