Perhaps you are right, but still the argument seems highly contrived. For example,
The cook kneads the dough to make bread.
With knead, the object is required. You can shift it to the passive,
The dough is kneaded (by the cook)
where the adverbial phrase is optional, but I don't know if linguists would label it is as passive transitive or intransitive, since we're still talking about an action taken on an object by an unnamed subject.
I think you're starting to get into the fine distinctions of how to label things, a subject primarily of interest to linguists (and not to everyday speakers like myself). See for example Ambitransitivity which I think is a better label for most English verbs.
Many English verbs are both transitive and intransitive, but the meaning changes if you exclude the object. For example:
He smells the brewing coffee
Even if you change the first sentence to the passive,
The brewing coffee is smelled by him.
I think it's likely it would be labelled as passive transitive and not intransitive. For example, here's an opinion by a blogger who asserts "all passive verbs are transitive".
Meanwhile, "He smells" (which, in case it's not clear, means that his body emits an offensive odor) is without object and definitely intransitive, although possibly better labeled as reflexive (or maybe pseudo-reflexive since it's other people who are actually smelling him).
(Edit) The point of the passive tense is to allow the speaker to relate the action and the object of the action without revealing the subject. If I say the dough was kneaded, the dough is not doing its own kneading. The passive voice doesn't magically change the object into the subject. As I said from the start, that argument seems tenuous at best.