As someone who regularly doesn't sleep I am going to go ahead and say this is probably bullshit. Even pretending to sleep is better than not sleeping.
Upon reading the article I think the title is just misleading. What can be said is that regularly getting only 6 hours of sleep will cognitively impair you in similar amounts to not sleeping for a few days but is less noticable because you have time to get used to it. This does not account for the physical effects of not sleeping for a couple days. Calling it "just as bad" is a gross generalization.