Back in February, Valve released the source code for Team Fortress 2 (TF2) into the Source SDK, which allows modders to see how it all works and get their standalone mods onto Steam. But also, it allows them to fix up issues directly in Team Fortress 2.
I always want symmetric licensing for community contributions. I have the same stance for Canonical and their Contribution License Agreement that also gives Canonical the exclusive rights to sell proprietary licenses.
This is a general stance I have, no matter who it is.
Valve does symmetric licensing for their SteamOS components, so there is precedent.
Also, I think you read way more into my comment than I actually meant, as if “sour taste” is the same as making demands.