Liverpool are briefing the press that the clause only requires them to inform Suarez of the bid (and possibly allow him to talk to the bidding club) - not force them to sell.
I know this discussion has been round the houses a bit but it seems like a pretty pointless clause that just wastes everyone's time i.e. Suarez and Club X thrash out a deal and then Liverpool veto it.
I suppose the idea may have been that Liverpool felt over £40m would be around the sort of level they'd give genuine consideration to offers and were happy to include the clause if it kept Suarez's agent happy. Still a bit bizarre though as you'd have thought Suarez camp would be pushing hard for a genuine buyout figure rather than a trigger point for dialogue which you'd expect to happen anyway most of the time.