First of all, the skepticism of meta-narratives is not a prescription or a principle, it is an observation Lyotard made of the effect that the broader context of postmodernism has on people. It is not proposed as the appropriate reaction, much less the only one. It is basically impossible for an observation to contradict itself in principle rather than in fact.
Second, you are identifying the most annoying thread of postmodernism 'Critical Theory' as the whole thing. People like Quine and Wittgenstein, who helped break down the relevance of metanarrative by killing off Logical Positivism were not preachy, politically obsessed post-Marxists. But they are clearly part of the move to curtail modernism... Lyotard worked from Wittgenstein, and spawned Habermas, et. al. The loudest aspect of a theory is not generally the most reasonable. But even this theory, since it arises within the context of postmodernism contains principles that try to keep it from being a metanarrative.
Intersectionality, another principle of this and other aspects of modern postmodernism, implies that no single one of these narratives of oppression can be taken independently of all the others. So no, no one of them is a meta-narrative, because individual lived experience, which is actual narrative and not 'meta' is the only fully intersectional application of the notion of oppression. Otherwise, labeling an oppressor is just stereotyping.
(It does not generally succeed well: People who talk about intersectionality often are hypocritical and don't actually act accordingly. Most of them have, for instance, unremediated notions of Evangelical Christians, who have begun, in this era where everyone is influenced by this theory, to see themselves as oppressed as a consequence of being stereotyped as an oppressive influence.)
And intersectionality is not a narrative that amalgamates all those other narratives into a single one. It is a principle. Critical Theory uses it to combine and analyze narratives of oppression, knowing that this must be done casewise and cannot be coordinated into a metanarrative. But in itself, it has no contents, and you can't call it a narrative. Various real scientific facts, like observations about gender heteroschedasticity, are instances of intersectionality, and they undercut the feminist narrative of oppression.
If the only application of Critical Theory including this principle is in concrete terms, it is not at any higher level of abstraction -- it is not 'meta'. That is one reason why people who write about it try to continuously lard in data and end up speaking in convoluted and confusing backtracks. The point isn't that all generalizations are evil, but that generalization must be grounded in a way that admits it is a construct based on individual observations. If it is not grounded, people are not really acting according to the principles they are stating. What's news there?
Besides, if a purposely postmodern theory did not refute itself when viewed at any pointlessly high level of abstraction, wouldn't that be contradiction to the main content of postmodern thought itself? That thread is mostly about how:
- most ideas are social constructions
- most powerful social constructions are riddled with internal contradictions,
- so we need to limit our reliance on abstraction
- because abstraction and general perspective remain excessive in our modern narrative?