That's a lousy "figure of speech".

I'm normally in favor of giving people the benefit of the doubt and reading what they meant rather than what they literally wrote. I couldn't tell what the hell your point was in writing that though. You definitely won't make any progress in arguing with anyone by just making flatly incorrect statements as the core of your argument. Even people who would otherwise agree with you are left scratching their head.

Qualifying words are an oft overlooked tool in language. Especially when someone is presenting an idea you disagree with.

Humans often use analogies, exaggerations, representations, examples, and other linguistic tools to attempt to convey their points. But speech is far form simple. If you interpret words as they are, you will always fail to communicate. Words are an attempt at conveying the thoughts in one's head. Never trust the person that is bold enough to claim that they are impossible to misinterpret, because they are an immutable force and the main character in their own reality.

That is the quote.

It would be absolutely unreasonable to believe that 100% of Texans (or literally any demographic) is united on any issue.

You are correct that the OP did not use a qualifier, but that is not the only form of miscommunication I mentioned (this one is called "hyperbole", a form of exaggeration, which was explicitly mentioned). So if you're going to complain to me about "lecturing" you (I'm not), you should probably demonstrate a reasonable interpretation. You got downvoted because a lot of people are quite used to this extremely common pattern of speech. It is okay if you are not, but learn from it and move on instead of doubling down.