I've sent a message to the user to discuss this. It's not uncommon for tag wikis to be seeded with the 'elevator pitch' from an official project or product front page. However, citations are positively mandatory and we much prefer that original, first hand knowledge goes into the wiki, being the majority of the content.
In the future, It would be better to flag something like this for our attention. If you see someone making what you feel are questionable wiki edits, flag any of their questions or answers, select 'other' and tell us to look at their history, specifically at wiki edits.
Thanks for pointing it out.