It's not.

Why not use and/or enhance already existing free software replacement, used by projects like freesmartphone.org or... Replicant?

Most of the popular ROMs are made using the very same closed drivers the article is talking about to provide hardware compatibility - otherwise they would be exactly where Replicant is now.
Any third-party ROM for Galaxy devices that uses Samsung's library to communicate with the modem is vulnerable - so almost all of them are, including CyanogenMod.

Modem can ask the APU app to write/read selected files and do some other file system operations. Why would modem want to read/write arbitrary files on user's file system and what and how could invoke such behavior of the modem? The answer is up to your imagination.

Well, in fact many other phones don't need any backdoor to do the same as lots of them have modems directly connected to main RAM, exposing it to monitoring or even manipulation by the closed and strictly secured modem firmware.

That's why projects like Neo900 opt for clear APU<->modem separation as host<->peripheral, together with power and antenna usage monitoring and fully free software stack on APU side.

This is part of their undocumented protocol for communication with the modem. Modem can ask to read or write some file on disk using IPC_RFS_READ_FILE, IPC_RFS_WRITE_FILE, IPC_RFS_LSEEK_FILE, IPC_RFS_CLOSE_FILE, etc. messages and the library will happily do that for the modem. It's hardly unintended.

Well, in fact, systemd can only be used with the Linux kernel (unless some other kernel mimic all custom Linux interfaces systemd relies on) - that's why it's becoming default for Jessie only on Linux architectures, while others, such as kFreeBSD or Hurd, will still use sysvinit.

Aside of the comment you're answering to being wrong, the full Debian OS on one of supported Linux architectures is officially called "Debian GNU/Linux" by Debian project itself.

Linux architectures, not GNU/Linux. In this context it's not about the whole operating system, it's about the kernel itself. Aside of Linux architectures there are also kFreeBSD architectures in Debian - with "k" added to make it clear that it's about FreeBSD kernel, not OS.

Don't try to fix other people when you don't know what them (and in turn you as well) are talking about.

Then how is it on topic if the answer was about pages requiring you to use JS to work at all?

openBmap, anyone?

Beat that, suckers.

It's directed at niche target. I'm actually positively surprised that it reached 200 this fast.

Have you actually used the N900 touchscreen? I wouldn't replace it with any capacitive crap.
https://www.youtube.com/watch?v=66RBfrBgL2E

Sure, those are the components and those are manufactured wherever Texas Instruments, Panasonic and other vendors manufacture them. The Neo900 itself will however be assembled in Germany, as that's the best the project can do with its resources (similarly to what Raspberry Pi did with assembling in UK).