I'm just guessing, but when you take Anavar without test, it will shut down your natural test production. No test = no conversion to estrogen = lower estrogen levels = gyno going away. Certainly not the most efficient way to go about it, as low test has it's own issues, but to each his own.
Makes more sense to me than steroids that can cause gyno making gyno go away. This is why anecdotes are not science, and I appreciate the research based knowledge around the parts.