In fact, I'd go further. You'd be hard-pressed to find anyone who is involved in free software business or in planning strategies for the community's future who would disagree with the sentiments out-of-hand.
If anything, a comment like Zemlin's is easy to make because -- as several posters pointed out -- Microsoft would undoubtedly refuse the conditions. Moreover, should Microsoft ever agree to them, the agreement itself would be an indication of how much the company had changed, and the transparency of the community process would be the best safeguard against any underhanded tactics. Should Microsoft try to renege on the collaboration, the openness of the process would make any duplicity obvious immediately.
Contrary to some of the claims, Zemlin's comments contained no talk of "giving in" or of extending unconditional trust to Microsoft. Nor is talking of interoperability enough to damn him -- or, if it is, then the Samba team should be condemned for signing an agreement to have access to Microsoft documentation.
So why the quickness to condemn Zemlin? The answer, I think, is that Microsoft has been the enemy of the free software community for so long that many of us have trouble thinking sanely about it. For years, Microsoft was the dominant threat to free software, and opposition to Microsoft was how you identified yourself as a true member of the community.
Now, free software is well able to protect itself, and the community has a set of ethics and a list of accomplishments that can be the core of a self-contained identity. However, in many corners, the old either-or thinking still lingers.
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In this mindset, everyone is either resolutely against Microsoft or else a traitor or a dupe. No neutral position is possible. According to this way of thinking, a true supporter of free software could never support collaboration with Microsoft, so anyone who does is self-evidently either pro-Microsoft or badly deluded.
Furthermore, to raise the possibility as casually as Zemlin does only compounds the offense. The casualness suggests that the step would not be so momentous as the years of angst demand, or maybe even that the old either-or thinking is obsolete. Both these ideas are unthinkable to those whose identities as free software supporters is based on opposition to Microsoft, so they have to reject comments like Zemlin's as loudly as possible, simply to preserve their sense of who they are.
In theory, it should be possible to hold a less simplistic view -- one that is fully aware of Microsoft's history of sharp practices, but does not panic like a rabbit that sees the shadow of a hawk whenever the company is mentioned. And this is the view that Zemlin is working toward when he dissects Microsoft's recent announcement that it would allow limited access to its documentation as a move to "placate regulators" and as an effort to compete with new expectations of openness in one breath, then considers the possibility of collaboration in the next. However, the reaction to Zemlin's general and innocuous comments show how far away a more reasoned position is for many of his detractors.
Free software does not much need collaboration with Microsoft. Moreover, the cynics are probably right that it could never happen and wouldn't work if it did. All the same, there's no reason for condemning the idea in the abstract. If an agreement is made, and if it contains flaws, then there will be time enough for condemnation.
Meanwhile, publicly considering the possibility is harmless. If nothing else, doing so emphasizes the ethical superiority of free software -- and that's an idea that's worth planting in people's minds.