Sorry, but those arguments seem flimsy to me. I still fail to see how this would justify calling "optional" something that requires manually tinkering with files to avoid it being forced onto you.
I cannot accept apples being called oranges just because it's pratical. Apples are apples, oranges are oranges and an installer that by default installs a client not giving any option to avoid it has nothing "optional".

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It doesn't require any tinkering, it's only the shortcuts, if you don't use the default shortcut and launch the game directly from the exe it doesn't start Galaxy. Again we are talking about the retail version, most peoples who buy the retail version nowadays expect it to be "plug in play", they expect it to automatically appear on their Steam collection, they don't expect to have to go to Gog and check if there is a patch to download.

You can run the game without using the client therefore said is optional, you can uninstall the client and still run the game. Is it the most practical thing for those who don't want to use the client ? of course not, but does it makes the client any less optional ? no.

I think it's more of the principle of the thing than the technical term.
If I lock you in a cell and tell you that if you scratch through a patch of dirt in the north wall, it'll bring forth a ray of light which will hit a brick in the cell, and if you count 36 bricks up, 12 left, and 14 right from that brick, then take two steps backwards, spin around, and jab your finger straight out, you'll find a loose brick behind which is a complicated disco guide, which, if you manage to flawlessly perform while dancing to ABBA's "Dancing Queen" in your head, will cause just enough pressure in just the right places on the ground to open a secret panel that contains the key to your cell, can I say you're a free man?
After all, you can leave anytime you like, just follow the instructions above. You're not really trapped. You staying in your cell is completely optional.

Even on principle it's different, contrary to your example they didn't put any process in place to prevent you from running the game without the client, you don't have to follow some weird custom procedure or do some outrageous things to make it "optional", you just need to either click directly on the game exe (something fully standard) or uninstall the client (again standard Windows procedure)

Your example would be the equivalent of having to go patch some binary, replace some DLLs, alter the registry, etc... but here, to use a better example, it would be to be you are put in a cell with the door wide open.

Again, I disagree on both assertions, but we are going in circles with the discussion, therefore I guess we'll just have to agree to disagree.
Everyone is entitled to their opinion, and I already made my point.
If you are happy with how it works, good for you. I'm not.

That's kind of the point.
Fair enough, my examples tend to be humorously exaggerated. If you want a more accurate one, I would say more like you're locked in a cell and given the keys to unlock it with. I dunno about you, but personally, I'd rather not be locked in the cell to begin with. Especially not every time I want to download a game.

No. It may have forced you to install it, but by your own admission in your previous post you don't have to use it. The shortcut put there by default is not forcing you to use Galaxy as making a shortcut to a program on your computer is elementary computer use.

Wrong. It is if the executable file is in the same directory, not if it's hidden in some obscure sub-directory.
Anyway, even if it weren't, the point would stay. An option in the installation is the optional way. Forcing a user to create a shortcut himself means requiring him to do stuff outside the interface you provide, hence not at all "encouraging". It's forcing, period.
I used to create installation discs for business software as part of my job, therefore I know a thing or two about what I'm saying.

No idea if this was TLD devs or gogs mistake, but.... I DL'd the (late) The Long Dark release, the none galaxy versions of course, but look what is plastered on main load screen...

I imagine the dev's have referred to the Gog version (as opposed to the Steam version) as Galaxy Release.
Presumably it does have some kind of Galaxy integration, but if you don't have Galaxy installed it shouldn't do anything as is usually the case.

Perhaps encouraging is too soft a word, but forcing is too strong. I don't actually disagree with you that it's a bad thing, I just disagree they are forcing anyone to use Galaxy. It would only ve forcing with Steam-style DRM.