I think the telling bit about the "invasion plan" is the telling bit. That is, Sela freely tells the plot to the captured trio and then allows them to escape. So we can pretty safely assume that everything that was told was a lie. Except for those parts that were devious double lies, of course.
(On a similar vein, and relating to the real-world precedent of fundamentally faulty infiltration plans, the Nazis infamously sent
extremely ill-chosen and ill-trained agents to infiltrate Great Britain during WWII, these then being captured en masse and turned against their original operators. This was apparently because the German spymasters were opponents of Nazism and did everything in their power to prevent the acquisition of relevant information - the infiltration operation was mainly the work of Abwehr, a profoundly and successfully traitorous intelligence service that managed to undo many of the achievements of the other German intel agencies. Picard has been sent on missions like this in several episodes, such as "Chain of Command" and "Gambit"; apparently, somebody at Starfleet Intelligence or Starfleet Security wants him to fail! Although not necessarily to the detriment of the UFP.)
"Vulcans are pacifists" is a statement made by the ignorant Kzinti in "The Slaver Weapon". They are proven rather wrong when Spock beats them to submission...
Surak of Vulcan is also credited with establishing Vulcan pacifism in "The Savage Curtain", but he only
a) chooses his enemies wisely when saying there's no point in fighting the images of Kahless and Genghis Khan
b) says that toning down the original Vulcan violence saved their species and serves as an example of a negotiated, nondestructive solution being at least possible
which establish his personal deep rationality but not a general Vulcan tendency to shy away from fights.
Timo Saloniemi