Postmodernism absolutely does not deny intent. In fact, motivation behind texts/speech (as well as interpretation by readers/hearers) is such an important part

Postmodernism absolutely does not deny intent. In fact, motivation behind texts/speech (as well as interpretation by readers/hearers) is such an important part of it that you can't really do postmodern analysis without accounting for motives. The closest thing I can imagine for any kind of defense of your statement is that postmodernism will not let the declared or conscious intent of the speaker absolutely constrain a text. The logical distinctions between "not absolutely constraining" and "declaring it to be completely useless" should be clear. And the idea that people don't always declare their intent accurately should also be uncontroversial. Really, postmodernism is essentially very big elaboration on the principles underlying Sinclair's observation "it is difficult to get a man to understand something, when his salary depends on his not understanding it."