Natural Selection works only if the unfit don't reproduce at the same rate as the fit. Since the percentage of humans born who eventually reproduce is at massively high and unnatural numbers, it goes to follow that there is little Natural Selection affecting the population genome.
There are numerous sources saying the same. Consider, for example, Sir David Attenborough: Humans have stopped evolving
Human beings have stopped evolving after becoming the only species to “put halt to natural selection of its own free will”, Sir David Attenborough has said, as he predicts the “cultural evolution” of the future.
Sir David, whose new show concentrates on the ascent of man, said he believed humans had now stopped evolving in physical terms, after developing means to keep even the weakest of the species alive.
Saying we are now able to rear up to 99 per cent of our babies, he added people were no longer subject to Darwinian theories natural selection.
Save for reproductive issues that medicine cannot overcome, there's no reason to think that the unfit reproduce more or less than the fit, when averaged out among the world's billions of people.
If it's good enough for Attenborough, it's good enough for me.
Now, the claim in the question's source goes a step further, saying the human genome is deteriorating. Maybe, but that's really a matter of perspective. If medicine can keep up with mutations and genetic drift that would otherwise be harmful, then it doesn't really matter. And if it can't keep up, well then Natural Selection will kick in again.
A more neutral term would be the human genome is "broadening". But this can be viewed as a good thing to. With a broader genome, the species is more likely to survive devastation from sudden environmental change, such as a plague.