I worked at the Wikimedia Foundation from 2012 to 2016. The Foundation did fly me across the world several times, either to attend professional conferences like FOSDEM or (more commonly) to participate in events hosted by a local chapter, like a community hackathon. I never flew anything but coach. I can recall one occasion when a colleague was able to get a free upgrade by using his frequent flyer miles. I am not aware of the WMF ever paying for business class for one of its employees.

This sort of comment is really pernicious. If you bring up such an accusation, you should really be prepared to back it up.