The Bitcoin Foundation in no way owns or controls the Bitcoin core implementation hosted at github.com/bitcoin.
You are right, they don't... but they do fund a Chief Scientist position, amongst other things, and they regularly make decisions about what to commit grant monies to. I understand that they don't control the core implementation, but I think that the funding decisions they make need to support better both basic development as well as prioritizing for anonymity.
The Bitcoin Foundation currently sponsors some of the work there, since that is currently a good way to support the ecosystem— but this may not always be the case, and in the future the Bitcoin foundation may better spend its funds supporting the ecosystem in other ways (including other technical ways).
There is nothing in the bylaws that currently requires the Foundation to support bitcoin at all with member funds. As a member, I'd like to see that change.
As such, I don't think the the bylaws should single this out.
Without something in the Bylaws requiring it, there is nothing that would motivate the Board to do so. It has begun lobbying in Washington, D.C., as an example of the use of its funds. I believe the funds would be better spent on development than lobbying unreasonable organizations (such as governmental ones), so I do think the bylaws should single this out. In addition, even if I do a pull request on it and it is shot down at the Board of Directors level, they'll be on the record with respect to their position on it.
I do not know if the BCF accepts restricted donations, some organizations do— some do not— if they do then thats potentially a way you could better target your funds. Additionally, there are other groups and indivigual developers working in the ecosystem who's work you could support directly and separately from the foundation. Increased diversity of support is good for the ecosystem and you may be able to support work which better aligns with your concerns and values than the initiatives currently being undertaken by the Bitcoin Foundation.
The Bylaws contain no restrictions on what the funds from member dues (or any other funds the Foundation may receive) can be used for. None whatsoever. My proposal suggests a focusing, with some emphasis on prioritization. It wouldn't bind the hands of the Board, but it would provide incentive and a reference point in the Purpose of the Bylaws for charting a more serious path forward to protect the users.
It may also be that some of the work you'd like to see done would best be accomplished outside of Bitcoin core— because the importance of the software is so high its a more challenging platform to experiment in. It can be easier to prove and refine an idea outside of it using other software on the network and then implement it back in Bitcoin Core once the design is clear.
I can see from your remarks you may be referring to the Zerocash project. From what I understand, the bitcoin development community has offered no assurances or support to the zerocash project of the variety that would entail working together to integrate the zerocoin/libzerocoin code (or the refined code of the zerocash project) into the bitcoin protocol. Thus, the Zerocash project is working on an alternative coin system in which different cryptocurrencies would be basecoin that could be exchanged for Zerocoins. This convolution would not be necessary if bitcoin development was more friendly to anonymity systems developers. The kind of anonymity development I'd like to see happen must affect the basic bitcoin protocol. A failure to do this ultimately will not just doom the Foundation to a subservient role in terms of its relationship to the state, but as well, will compromise the ability of any bitcoin users, anywhere, to be able to use bitcoin without being threatened by malicious individuals, thousands of corporations, and numerous governments (such as, but not limited to, NY State (USA), the U.K., China, and the Russian Federation). This is not rocket science, it is a fact. In addition, if basic bitcoin development issues cannot be well-funded and dealt with quickly, then it is much more difficult to move on to more advanced development issues, such as either privacy enhancements or anonymity development (which currently doesn't exist in bitcoin). If bitcoin (whether through the Foundation's funding of different activities, or through the activities of developers) doesn't find a way and chart a clear and simple path to accomplishing these funding objectives, not only will bitcoin falter as its users are subjected to all kinds of penalties and problems, but people who compare bitcoin to other systems will want to leave it, choosing instead alternative coins or implementations that provide some anonymity, such as Zerocash project or Bytecoin(BCN), and/or similar projects that may emerge in the future. I wish I could say that bitcoin's future is bright, but if the Foundation and developers alike can't see through this to the other side and start really emphasizing funding of basic bitcoin development as well as charting a clear path to anonymity development, bitcoin users will ultimately decline (or be subjected to penalties in different places around the globe that will compel people to leave bitcoin and choose an anonymous and decentralized system instead).