Seems GPL2 or GPL3 already requires this

* The FooBar application, licensed under AGPL 3, has some networking functionality (which is elaborate enough that users can interact with it remotely), and is freely available (with source, full attribution, a copy of the AGPL, etc.) on GitHub. It does not have any feature that allows remote users to directly request a copy of its source code.
* You fix a typo or other minor bug in the FooBar source, commit the changes to a local Git repository, and send a pull request to the FooBar maintainers. You only fix the typo, and do not add a feature allowing remote users to request source from the application.
* The FooBar developers add a "request source" function to the FooBar application. It is implemented using mDNS, which relies on broadcast packets to work. You don't like broadcast packets on your home network, so you patch this functionality out in your own private copy of FooBar. This patch is never redistributed to anyone, and the binary is only ever used on your own private LAN that nobody else can access. For good measure, you hide the FooBar application behind some kind of client-authenticating reverse proxy, so that you can be absolutely sure that it has no remote users other than yourself.
* Alternatively, you stick your copy of FooBar behind a router or switch that is configured to drop broadcast packets.
* You make a FooBar instance accessible over the public internet, after making some minor modifications to it (all of which are contributed upstream via GitHub pull requests, so your copy of FooBar is identical to the public source code). But broadcast packets are not going to be routed over the public internet, so the source offer presents an unusable mDNS domain (your changes never touched the source offer part of the code).
* You change the link to point to the public GitHub, but upstream refuses your pull request (arguing that FooBar should serve its own source code without relying on GitHub or any other third party, and claiming that mDNS is "good enough" for their intended use case on a private LAN), so now you are presenting a source link that does not exactly correspond to the binary you are running.