There sure are a lot of confident yet highly speculative declarations about life in that article, in spite of the fact that we currently only have a sample size of one.
> The aliens are silent because they are extinct
> new life would commonly die out due to runaway heating or cooling on their fledgling planets
I'm not disputing the science or studies the article refers to (I'm far from qualified for that), I believe that models of plausibility are an important part of the process, but as with most science journalism they just can't help turning them into some sort of "absolute" statements.