'Alarming' DeviantArt Submission Policy

Apparently Hot Topic started selling a shirt featuring a popular artwork uploaded here on DeviantArt without that artist's permission. Tumblr Post

Okay then, reliable-fount-of-information-called-Tumblr. Does deviantART have the right to sell the art people upload?
TLDR: No.

Let's look at DA's Terms of Service and policies. I translated all of the relevant policies you agreed to when you started using the site.

Terms of Service

4. Copyright

deviantART is, unless otherwise stated, the owner of all copyright and data rights in the Service and its contents. Individuals who have posted works to deviantART are either the copyright owners of the component parts of that work or are posting the work under license from a copyright owner or his or her agent or otherwise as permitted by law. You may not reproduce, distribute, publicly display or perform, or prepare derivative works based on any of the Content including any such works without the express, written consent of deviantART or the appropriate owner of copyright in such works. deviantART does not claim ownership rights in your works or other materials posted by you to deviantART (Your Content). You agree not to distribute any part of the Service other than Your Content in any medium other than as permitted in these Terms of Service or by use of functions on the Service provided by us. You agree not to alter or modify any part of the Service unless expressly permitted to do so by us or by use of functions on the Service provided by us.

16. Copyright in Your Content

deviantART does not claim ownership rights in Your Content. For the sole purpose of enabling us to make your Content available through the Service, you grant to deviantART a non-exclusive, royalty-free license to reproduce, distribute, re-format, store, prepare derivative works based on, and publicly display and perform Your Content. Please note that when you upload Content, third parties will be able to copy, distribute and display your Content using readily available tools on their computers for this purpose although other than by linking to your Content on deviantART any use by a third party of your Content could violate paragraph 4 of these Terms and Conditions unless the third party receives permission from you by license.

Copyright Policy

This page shouldn't be called a "policy" because it isn't. The page explains copyright basics. It has instructions on what to do if someone uploads your art to the site and infringes on your copyright.

Submission Policy

Lots of words.

You agree to the rules when you upload a piece of art. You can end the agreement at any time for any piece of art by deleting it from the site.

Each artist keeps the copyright and ownership of the art they upload to the site. By uploading a piece of art, you give DA a royalty-free license so that they can display it on the site without you suing them. You give DA the right to:

1) Electronically publish your art or pieces of your art.
2) Resize your art, make collages, and "alter" your art in similar ways.
4) Use your art to market and advertise deviantART.
5) Use your DA name, profile, and bio to promote and market deviantART.
6) Give any of the above rights to other people and companies through a sublicense. Note: This is probably so DA can hire outside advertising companies to make ads about deviantART and stuff like that. It does not allow DA to sell your art to third parties.

DA must get permission from an artist to use their art for any commercial purpose.

If somebody steals your art on DA and makes shirts out of it, DA has indemnity. This means you can't sue deviantART. Instead you have to go after the person who stole your art

So did Hot Topic steal your art? Go sue Hot Topic.