I think a nice example that could help clarify the situation is the CLA that Canonical uses; if I remember correctly they reserve to themselves the right to change the license of community contributions.
Looking at the Canonical CLA [1], you're right that it allows Canonical the right to relicense contributions under any other license:
> 2.3 Outbound License
> Based on the grant of rights in Sections 2.1 and 2.2, if We include Your Contribution in a Material, We may license the Contribution under any license, including copyleft, permissive, commercial, or proprietary licenses. [...]
However, please note that my original comment [2] was asking for a CLA which prevents usage in a proprietary setting, while the project is under a permissive license like Apache/BSD/MIT (emphasis added):
> I've never seen an Apache/BSD/MIT project where the CLA (and only the CLA) prohibits commercial / proprietary / closed-source or any other use cases — if you have an example or two, could you please point them out?
It was not directly a reply to that case, it was meant to say that even if the license was GPL so that a proprietary fork was forbidden, a CLA could make it so that only the owner of the project is allowed to use your contributions as proprietary.
It was an example of a case where a CLA could have caused what was imputed by the original comment.
