Given their success, I would have recommended that they proceed with the strategy they followed - of course.

Since one is usually not in possession of such knowledge of the future, the general rule I propose is that one must have a plausible strategy for either building a third party or influencing the existing major parties depending on circumstance. And in particular the strategy of "let them know our displeasure by making a protest vote or not voting" is one that has been shown to not work.