> If a developer or company has no pecuniary motive for proprietary relicensing, why would it bother to use copyleft for the project to begin with? Better to allow noncopyleft use by all; what is socially gained by permitting occasional discrimination (particularly where, as your comment might imply, the discrimination is always in favor of a commercial entity)?
It is true that several companies use copyleft (mostly GPLv2) in order to attract more attention and developers on their software and sell proprietary licenses with other terms to people who pay. I don't see any harm on that, but even if you think there is harm by someone being treated differently, I don't see why punish this company at all. They released their code as free software anyway (assuming they play fair).
What the license looks to me, is that it says, that if you have a business model that allows you to develop and release free software then we take it from you. It doesn't sound about code being free to see and modify.
You may have a point on companies abusing the copyleft terms. In that case you have to be explicit and justify those clauses, because their reasons are not apparent.