Truth be told I think Valve can certainly ease up with the restrictions. Compared to Valve, EA is a shitty company that treats its customers (and apparently its employees) like crap, but that doesn't mean Valve's nose is clean in this matter.
Allow the game on Steam and let the publisher do what it wants with its DLC is what I would suggest.
“The greatness of a nation and its moral progress can be judged by the way its animals are treated.”
- Mahatma Gandhi