I can see where the author of that article is coming from. In my very non-expert opinion it's far too early in the study of the origins of life, and in particular of complex life, on this planet to be able to say in a meaningful way that intelligent life is so improbable, though. What is true is that the life/ intelligent life barrier is harder to cross than the no-life/ life barrier, ie "life", in a loose sense, is probably almost inevitable given energetically-favourable conditions, whereas I can accept that intelligent life requires rather more luck.
One way or another though, the only way to know for certain is to go to other worlds, or to investigate them from as close a distance as possible. In practice, observing the Universe from here and hoping to find confirmation of life is very, very difficult. There are ways to make some progress, but it's usually going to be tough to rule out the alternative "just a natural non-life process" for any signature you could care to look for.
We (almost certainly) aren't going to find anything life-wise at Alpha Centauri anyway, but even then the prospect of getting a meaningful experiment over there would be huge on its own; and once you've taken that step, the rest of the galaxy is open to us; or at least, say, everything within a hundred light years or so. At any rate, there are presumably worse things to spend a few billion pounds on.