I consider myself a free software supporter, although I wouldn't go so far as to call myself a zealot.
I've worked in environments where the people supported free software all the way, and I've worked in 100% proprietary shops where there wasn't a single FOSS program in sight. I can't say I ever found it hard to stick to my ideals on either of them.
On the former the "rub off" effect is there and it's business as usual, on the later you might feel tempted to adhere to the views of those around you, but actually having to work with a proprietary software stack and its developers makes you truly appreciate the beauty of free software, so it's not exactly hard to be constantly wishing for those greener pastures you know are there just over the hill.
That being said, I'm also a gamer but never felt the need to have access to any source code, due to the simple fact that it's "only" entertainment. The game isn't running my servers, or filtering my e-mail, or storing my data. These are tasks where I demand the absolute control that free software provides, games, on the other hand... just aren't as important.
I feel about as much need to have access to a game's source code as I do to have access to the 3D models used in a movie's CGI effects. They could be useful to about 0.5% of the people watching it, but for the rest of us "users" it doesn't really matter.
It *could* be useful to have access to the source code, but for another reason altogether you don't seem to have touched upon: Availability. It ensures that if there's enough interest in what you've created, people will make sure it runs on whatever exotic platforms exist today or 10 years from now. And it's this lack of availability that I take issue with. You said that the release of Perfectionism wasn't met with any hisses and boos, well... maybe that was because the people who would hiss and boo haven't even heard of it, like me. Even though I played two of your previous games (Passage and Gravitation) because they ran on Linux, I hadn't even heard of Perfection until I read this. And how did I come to read this? Well, it was featured on braid-game.com, a site which I have added to my feed aggregator due to the fact that this game *might* have a Linux release, and thus of interest to me. Don't assume that people don't care just because they aren't vocal, maybe they just don't know about it.
So now that I do, allow me to hiss and boo at the fact that I won't be able to play these games.