You have missed the point entirely or just not bothered reading the article. Let me clear things up for you so that others do not get mislead to think you've made some brilliant finding that suddenly discredits this information. You've actually just dun goof'd.

western liberals

The researchers in the article are from the University of Chicago, USA, and the University of Oxford, England. Nowhere is their political affiliation mentioned, so on what grounds do you call them "Western liberals"?

telling people how their religion should be practiced

Their conclusions summarize what they have found through observation, and nothing else. Nowhere is any normative prescription about religion made, so no one in this article is telling anyone how any religion is to be made. This is a fact.

Saying someone who literally interprets the book and follows all of its commandments

Another fact is that the article says the exact opposite, and backs it up with research. An English researcher from the University of Oxford has observed the interview answers from imprisoned member of IS and found that they do not know what's in the book. The article mentions that many of them have not been living the commandments of the book. Go read about the life of Salah Abdeslam, the beardless Muslim (which is against the book!) who was just caught in Brussels.

In stead of making baseless claims, relate directly to the facts in the article. Bother to deal with the actual content in stead of just using this as another springboard to spreading whatever opinion you like at any given moment.

Let's look into your claims about the science of religion, a field of research at universities across the world:

the entire schtick with religion is that the holy book is, you know, holy

This says literally nothing. What does it mean that it is holy? Does that mean that its contents should be interpreted figuratively or literally? Are you aware of the existence of disciplines like hermeneutics (interpretation) and exegesis (scriptural interpretation)? These also exist within Islam. Islam does not agree on the message of "the book". In fact, the devil is in the details with all religions. This fact is so trivial that I don't feel a need to expand on it. Please look into the study of religion before you make weird assumptions about "schticks" and "books" and "holy". That would be a minimal of etiquette.