Does Discourse's contributor agreement provide an exit door from Open Source?

I’m concerned with the first point of the agreement (emphasis mine):

You grant to “The Company” (Civilized Discourse Construction Kit, Inc.) a non-exclusive, irrevocable, worldwide, royalty-free, sublicenseable, relicenseable, transferable license under all of Your relevant intellectual property rights, to use, copy, prepare derivative works of, distribute and publicly perform and display “The Contributions” on any licensing terms, including without limitation: (a) open source licenses like the GNU General Public (v2.0) license; and (b) binary, proprietary, or commercial licenses. Except for the licenses granted herein, You reserve all right, title, and interest in and to “The Contributions”.

I see two problems with this (b) point:

  1. it seems to suggest that the GPL is not a commercial license. But the GPL doesn’t prevent commerce at all. This is a common misconception.

  2. it seems to tell that the code is GPL (which forbids proprietary license) AND can be used to produce proprietary software. That is, it’s saying that the code should be licensed under the Apache 2.0 license (if you want to prevent patent treachery), or a lax license such as BSD-3 (which authorizes free software to be closed, as we’ve seen with Apple OS X, etc.), not the GPL.

This latter point makes me uncomfortable because it definitely contradicts the general discourse of Discourse and free software: e.g., section 6 of the CLA, or the famous “there’s only one version of Discourse, the awesome version.”

I’m ready to give my assent for GPLv2, which practically authorizes employing GPL code with proprietary modifications. What I’m not ready to do is sign a document that pretends I’m writing free software, while the code is aimed to be used in non-GPL-compliant ways as suggested by point ‘(b)’. I’d like to understand the logic behind this point.

My understanding is that this CLA gives an exit opportunity (in startup jargon) for the founders to sell the company to corporate sharks who would then be able to do whatever they want, including killing the product by making it proprietary, in which case the burden would fall on this community to keep a fork free.