Hmm, I don't know about that. After all, the Venezuelans followed through on their plans to invade Guyana in 1983, deploying thousands of troops there as part of their invasion force. That didn't break the union- if anything, it made the union stronger.
-Well of course, the Guyanese invasion made the union stronger. The "invasion" force was little more than a probing attack with the intention to only go farther if two conditions were found to be the case:
-The Guyanese population wasn't extremely hostile to annexation (they were).
-The British would not intervene (They did).
The first part is essential, which is why it's doubtful that Venezuela would have tried to take over the whole country-what little irregular resistance existed was nightmarish enough already.
You'd be hard-pressed to come up with a more patriotism-inducing war. Just enough fighting to make the myth of a heroic victory real, but not enough to strain the federation. (Again, very few Jamaicans were actually deployed to Guyana during the crisis). When it became clear those were not the case, the 'invaders' went right back across the border as fast as they could.
Now contrast that with the later disputes. You have a
lot of provocative intrusions into undisputed Venezuelan territorial waters, many instances where the first shots were fired by the West Indies, and a justified suspicion that Port-of-Spain was trying to induce a war and then call to NATO for help so that Venezuela would be permanently crushed.
The Pentagon suspected this as well, which is why they kept privately telling the WIF that they would not intervene. By this time, the newer Venezuelan leaders have learned their lesson and know how to play diplomatically.
So while Guyana was "Hooray, the British saved-we fought back" across the federation, a mass mobilization against a landing in Siparia would probably go "great, the Trinidadians poked the troupial and now they want us to bail them out."