The LOI is binding and the broad terms have been outlined and already agreed upon (i.e. royalty limits, global license, etc). Overstating things you don't know about is pathetic. You have no direct line of sight regarding the remaining negotiating points, and logic dictates that both sides had proper legal council and appropriately covered their liabilities.
Additionally, Ironwood only holds a flimsy method of use patent, not a product patent. And since they have failed to mobilize development activities towards commercialization of a product as defined under the Hatch-Waxman act, Synergy could have easily challenged and won (with high probability) a legal ruling without entering any agreement with Ironwood.
Bottom line: This agreement clears the way for SGYP to either partner or sell once they've cleared the clinical hurdle in early January.