If I wanted to refute the article, I would point out that aside from being in mice the researchers found a 'significant decrease in IGF-1 levels' after '24 weeks of continuous infusion'.
The full text said the dose was akin to 6 cups of green tea a day, so IF this decrease in IGF-1 would lead to a decrease in muscle mass you can just stay under that limit.
And that's a bit IF, who says that IGF-1 levels in the prostate, where they measured, correlate or are significant when applied to muscle tissue.
Hell, even if we assume the worst in all scenarios, the benefits of green tea on insulin sensitivity and fat burning would win in a cost-benefit analysis.
Until I see a direct study in regards to green tea affecting muscle mass accrual or preservation, I will continue to consume it by the pot.