Here is a thought. Maybe the use of the word “because” has nothing to do with it except that it escalates the potential for conflict.
Nobody wants to get into a conflict at the copy machine. If someone tries to cut the line without offering a reason, you feel more justified in denying them a place in line ahead of you because you know others are likely to side with you in a conflict should one occur.
If, however your denial of a forward place in line has any potential to be seen as arbitrary or even inhospitable to someone with a reason, you immediately believe that you may have limited peer support should a conflict arise.
This study does not indicate any value attributed to the word “because” beyond muddying the mental calculus one does to determine whether others will ally with you should a conflict arise.
If the situation were not so hostile as cutting in line, for example, trying to sell a car to a potential buyer, adding an arbitrary “because” offers no value and may undermine your sales efforts BECAUSE there is no concern of conflict arising should the buyer deny the sales pitch. On the other hand, offering a reason that aligns with the buyers wants, needs and values may prove effective in selling him the car.
Bottom line, this study proves nothing. It only illustrated the rapid deployment of human allegiance calculation when presented with a potential conflict. It highlights a self preservation response.