That is a random comment in a forum from someone who doesn't represent Flickr.

The actual TOS make no mention of whether you can have a business account or not. In face the best practices page specifically provides guidelines for businesses.

"This guide is intended to help organizations—such as businesses, groups and non-profits—get the most out of Flickr."

http://www.flickr.com/bestpractices/

Businesses do not need to be in the business of selling images in order to have a need to store images.

I just feel safer using Dropbox or Glacier. Flickr seems more like a social network, specialising in photos, and I wouldn't feel comfortable about using a service like that as a backup. As a business, the TOS are just not clear enough about what I can and can't store.

True, It's just the first thing I think of when "photos" and "business" come up.