Listen, you're still missing the central issue here. "It's" and "its" do not mean the same thing. Not even close. It's not like the distinction between "less" and "fewer" noted in the Stephen Fry video, where there's some sort of reasonable gray area in the usage. "Its" is a possessive form of it. "It's" is a contraction of "it is". So, this is what you wrote: "The phrase it is self is flawed."

Which is wrong. Full stop. This isn't being pedantic about grammar or usage. You used the wrong word. That's not something that you can defend from any kind of fortress of linguistic theory.

And, yes, we could figure out from the context that you meant to write "itself" or "its self". But we could also figure out what you meant if you wrote, "The phrase itsalf is flawed." The fact that we can decipher your writing is not the point. You weren't trying to employ creative, heterodox language here. You simply wrote the wrong word. And I think that you know that. You went back and changed it, as you would go back and change any other typo after it was pointed out to you.

If you changed it, why defend it? The correct response is, "Yeah, I wrote this in a hurry, and I used the wrong word." Don't get all umbraged and whatnot. Just fix it and move on.