There are significant differences between copyright, trademark, and licensing laws and what you con legally do, and/or get away with, in each case. Check here for starters
http://www.quiltingbusiness.com/quilting-copyright.htm
http://www.tabberone.com/Trademarks/...edFabric.shtml
The Steelers and all "tradesmarked" organizations, have invested huge amounts of time, money and effort in the creation and marketing of their trademark images. They are understanably quite concerned with how that image is represented to the public.