*sigh*
I suggest you read the rest of the thread. This matter has been closed, and you are incorrect.
Look in the PHB page 310, in the glossary. "Spells known" for a wizard means the spells in their spellbook. ALL of the spells in their spellbook, not just Read Magic. Hell you even quoted the text for the Spell Mastery feat. Did you notice that it says "choose a number of spells...that you already know"? That point, also, wasa brought up before.
This is a spurious claim. One you have no authority to make.
There's nothing "missing" from the line on page 7.
"In addition to having a high ability score, a spellcaster must be of high enough class level to be able to cast spells of a given spell level." is sufficient as a general rule. When you follow to the SPECIFICS of that rule, you can see that " their class has a numerical slot entry for spells of that level" ends up being what that sentence means, but that does not mean that lacking those words somehow makes it "not a rule".
You have no authority to declare it "not a rule", and one must accept that it it is "not a rule" for your hypothesis to be true.
Ergo, your hypothesis fails to be true by RAW.
"A broad statement that is then detailed" that you follow to a conclusion that ends up COMPLETELY IGNORING the "broad statement" means that you believe your extended inference and interpretation is more significant and rules-weighted than the actual text of the book.
So...yes. Superceded.
I didn't think it was necessary to re-iterate that, since your hypothesis also hinged on "somehow get CL boosts to get up to 17". Obviously caster level is also a restriction.
But once again, I contest that even if you could get CL-boosters to get up to 17 you would not be "able to cast L9 spells", because PHB page 171 is quite clear and distinct on what things that CL-adjusting effects apply to. And allowing the casting of spells of a higher level than one has access to was not one of them.
Because if that was true, then a level 6 cleric with the Evil domain who took a Faustian Pact for a L4 spell slot would be able to cast a L4 spell with the [Evil] descriptor 9because his CL would be 7). They cannot. The RAW do not support this.
Everything about your hypothesis hinges on your claim that "the rules don't explictly forbid this"*, which is Munchkin Fallacy. The rules must explicitly say that you can.
*And again, I am telling you that they do, you just ignore it and say "it's not rules, it's a descriptive statement".
BTW, I note you had no response to the fact that I pointed out that the PHB page 7 explicitly using the word "must" shows that it is a rules-imperative statement. Did you think that by glossing over it, I would forget that the point existed? I'll copy/paste it for you:
That sentence very clearly says the word "must", ergo it is a rules-primary imperative. "Must" means that it is a requirement. Furthermore, we are referred to Chapter 3, not for the actual rules, but for "details". That is, to say, the specifics of what this statement is saying. Because this statement about posessing class levels is, itself, a rule. The details of which vary depending on which class and which spell level one is discussing.
You disregard "must be of high enough class level" because it doesn't suit your purposes. Even in your (unauthorized) attempt to denigrate it as "a decriptive statement", it does not acurrately describe your hypothesized "Level 1 wizard with a faustian-Pact L9 spell slot and CL boosters to get CL 17", because that character is not of high enough class level.
Your hypothesis is not true by RAW.