The GPL, as many have commented, does not preclude or even discourage charging money for the software. The primary ethical thrust of the GPL is that your users must have unbridled freedom to use, modify, and redistribute the software you have provided to them. You appear to have met that cleanly.
But, as a considerate human being, you've also taken the time to consider the original authors personal wishes. That's a gracious thing to do, but obviously it's now landed you in an awkward position. Candidly, I'm with you; I'm rather biased, and think that folks deserve to receive compensation for their work on Free Software. However, it's up to you to decide how far to go in satisfying their personal wishes. So, it remains an interesting ethical dilemma, but I think it has nothing to do with the GPL.
Of course, if this is all a clever marketing stunt, and you're in cahoots with the original developer to create a fake controversy,
then my hat is off to you, sir.
One clarification: in my last paragraph, I implied that I was upset with people on the Wine mailing list. That was poorly written on my part; my anger is almost entirely directed at the original poster. Max has written some nifty code. Alexandre won't take it, for reasons that most folks are clear on. So folks are working to find ways to make that code available for folks to try. That's all good; it in fact makes good pressure for getting it done 'right', and makes it a great tool to test the usefulness of a DIB engine. So it's all good, and healthy, and for this to somehow be spun up the way it was really bugged me.
I find this story spin deeply offensive and highly misleading.
Let's start at the bottom, because that's the one that offends me so mightily. My blog is pointed to, with a caption 'adverse commercial agenda'. In that self same blog post, I refer to the energy we put into the DIB engine - I paid Huw to work on the DIB engine for six months. In fact, CodeWeavers has had the highly unenviable job of doing the long, hard dirty jobs that no one else wants to do, because they're not fun. (Can you say "COM", boys and girls). CodeWeavers contributes all of its patches to Wine first, and if you look at the top contributors to the Wine project throughout its lifetime, you will find a stunning number of CodeWeavers people. I find it personally insulting to the many people at CodeWeavers that have worked so very hard on Wine, often for very little pay, to imply that we have an evil agenda. We don't. We do want to make a living. We do put our customers ahead of shills on mailing lists. We do sometimes focus on making CrossOver better for specific tasks, but at all times our core mission remains making Wine better.
The proposed 'wonder' patch is based upon solid work by Jesse Allen, along with some of the work we paid Huw to do. And, in fact, it does some nifty things, because the author went after the fun cool part of the task, and ignored the long, hard, nasty part of the task. Indeed, the author repeatedly refuses to consider Alexandre's requirements for doing it right. Max has not 'satisfied all requirements set'. In fact, if you read this post, you'll see that Max has no interest in implementing the DIB Engine in the fashion that Alexandre has requested - it's too much work.
Wine has come a long way in the past 8-10 years - anyone who has used Wine lately can tell you how amazing it is becoming. This is largely driven by the ever increasing standard that Alexandre is using - the bar for patches, particularly against stable and well tested code - is becoming very high. This is a Good Thing (TM).
And finally, up to the top, this phrase is troubling: 'the dissatisfaction of core developers with the arbitrary project governance'. Once a year, the core Wine developers get together at WineConf. We often have a topic called 'Wine governance', where we have great fun lampooning Alexandre. (He certainly is terse, and can be incredibly maddening). But the overwhelming and unanimous consensus, year over year, is that he does a damn fine job and that the Wine project is lucky to have him.
Change that to be 'the dissatisfaction of a bunch of vocal people on the mailing list, who don't really understand the technical issues at hand, but think they're missing out on a cool shiny' and now you have an accurate statement.
Nobody said computers were going to be polite.