You're right of course, there were modifying circumstances that led to the result that they had. The Scout/Twila/Eliza thing certainly caused their strategy to be foiled, and Leanne had a pivotal vote (and made a remarkably bad decision) too.But they did have a strategy at one point, and that was to get rid of the men. Which would have been a good one, as it turned out.
But even if as a group they abandoned that plan and after that point didn't have a strategy, the lack of a plan is a very bad strategy in and of itself. And the net result of a group who were aligned at one point to vote off the men was that a man won. Six aligned women against one guy, and the guy won. With a majority of women on the jury, the lone male actually won.
That strategy, or lack of strategy, or even their inability to adhere to a strategy due to internal conflicts, was a very bad group strategy just based on the result if nothing else.
I won't argue that they deserve the all time "worst Strategist" title, Burton or even Sean may take the cake there, but the outcome of Vanuatu 6's strategy was a remarkable if explicable failure.