What is the flag made of? You can post a link to the photo here; that is allowed. With a link we could go look at the listing and possibly determine if it could be used for a quilt. If it's plastic, it would be much more difficult. If it's a slippery polyester, it could work. Since you are not a very experienced quilter, you would really need advice to work successfully with non-cotton fabrics. Even t-shirts require some special handling when making them into a quilt.
Edit: Although commercial fabric printing places cannot print the fabric because of copyright restrictions, you could print it yourself at home. Just need some specially treated fabric and a printer that uses pigment-based ink (because it is water-insoluble).