It is true that King Philippe
briefed to the media in 2015 that he wished to avoid having members of the royal family use the title "of Belgium" for professional advantage, but Laetitia's oldest siblings had already used it as their professional name for many years by that point (Amedeo was 29 years old in 2015), so it may be a matter of equal treatment between Laetitia and her older siblings (similar to the speculation about why Julian of Sweden received the same honors as his older brothers even though he was born after the King of Sweden restricted membership of the Royal House). Or perhaps she was not paid for the articles?
Interesting, could you share anything more about this friendship?