On some, they've even donated the same amount or more in total dollars compared to OS X users - ie, Linux users have been more profitable even though they have a much smaller market share.
In short, Linux users are very profitable (per-user).
[0] I can't confirm that it's 100%, but it's been every Humble Bundle I've participated in (a lot), which I think is a large enough sample size for the purposes of this statement.
Maybe the lack of games make Linux users appreciate it more?
Not to suggest that there actually IS any difference between the two groups when they pay - I just feel like more a good-deed-doing partner when I voluntarily pay more for something like humble bundle, that's all. It's silly and false, but it's definitely a feeling.
I'm not au courant with Linux in any of its various forms, so my assumptions above could be wildly wrong, of course.
I think that you are correct -- at least in part.
I have zero desire to play games but I have purchased many of the Humble Bundles, for example, simply to "support the cause" and encourage other vendors to also consider Linux as a viable platform. I usually give away whatever it is that I've bought.
A single, idealistic phone like this will allow those users to focus and buy it - in much the same way as the games.
Your comment isn't really as relevant as you think it is. It would suggest Linux would be a highly lucrative platform to target for games, however the more normal it becomes to port games to Linux the less likely people would be to pay that price. This would happen much faster than you would think too.