Qubes Debian templates have non-free/contrib (apt) by default

How can you decide whether a proprietary piece of software is harmful or not? You don’t know what it does, and it’s really hard to find out, by design. The last thing is the most important. You do not control what it does. Worse, it’s usually constantly updated, without you knowing what changes exactly. How about just “one piece of non-free software” in dom0, which downloads evil_script.sh via sys-net and runs it? I think it’s very much similar to a drop of poison in an otherwise normal dish. You can’t really have security without freedom.

Also, it seems you are thinking only in terms of security here. Free software is a tangential thing to security, it’s about freedom first. (People need both, of course, but sometimes we are put in a position to choose.) What do you think dangers of non-free software are?

Consider control over what your device is doing. Apple may keep your device secure (against common threats) but when you want to do something they don’t like, you are in trouble. You stop owning your device in a general sense.

If you only have one single piece of proprietary software, then you don’t control this piece and are at the mercy of its developers. You can’t fix it when it breaks or gets insecure (only its developers can, so it’s an artificial monopoly with all the consequences). You can only trust it, but you can’t verify. Different pieces of proprietary software can interact with each other against your will (like Intel ME interacting with their WiFi card). I recommend you to read more about the FSF reasoning why free software is important.

You can call me a “zealot” if you like, but I fail to see any logical inconsistencies in the above reasoning, and it proves true time and time again in the modern world.

How is free vs non-free classification non-neutral or non-objective? It’s based on what you are and are not allowed to do with software. It’s like a basic definition of what freedom or rights are. The classification is not about people or companies.

Nobody prevents you from disagreeing with the FSF judgment. They are entitled to their opinion just like you are.

Unlike software, the organic seal may be indeed impractical in the real world due to the complexities of the manufacturing. In case of software, the “impracticality” is artificially forced on you by the manufacturers. Nothing technical prevents them from releasing the code, only, presumably, their will for power over you. The FSF is fighting with this by educating public about the dangers of non-free software.

I don’t see how they don’t recognize the practical requirements. Does it mean that they should endorse it? Or stop warning about the dangers? By the way, Stallman was using a proprietary BIOS when no other option existed.

No, there isn’t.

Their fight is similar to the fight for the freedom of speech in a world of censorship. (Compare: world of non-free software, where you are fighting for the freedom of the users.)
The censors don’t allow you to express your disagreement and you are silenced. (Compare: all media constantly advertise proprietary devices showing their advantages and ignoring the dangers.)
People tell you that they are fine with the “small” proprietary pieces, because they do no harm to them. (Compare: “I have nothing to say, so I don’t know why I need a freedom of speech”.)
Wouldn’t it be incorrect to say in such case that your “insistence … rendered you largerly irrelevant”, because you do not simply follow the “practical path” of following the accepted norms? After all, many of the greatest advances in human progress began by having the courage to question unexamined assumptions that most people took for granted at the time.