Thanks for these reflections. A few thoughts in brief:
1) Any broad understanding, let alone application, of permaculture as a holistic design system is greatly hampered by a general lack of systems literacy in industrial societies, whose social norms emphasize linearity of process and reductionist cause-effect explanations. These same blind spots cripple our ability to govern ourselves harmoniously and effectively - at all scales and in all domains, from national civil governments to niche subcultures such as people involved in what they would call "permaculture."
2) "Permaculture" as a design system, absent specific application by humans, has no relatings with the political spectrum defined by default culture. Such relatings only exist between individuals and/or groups within the permaculture subculture. The risk, as you point out, is that "permaculture" as a concept may get associated too strongly with political positions of some practitioners, to the detriment of broader understanding of what permaculture as a design system offers and invites. It's a difference such as "permaculture is located at XYZ on the political spectrum" vs. "some people (who also happen to practice permaculture) are located at XYZ on the political spectrum."
3) In nearly 30 years of observing and interacting with permaculture subculture, I've seen various intentional and unintentional attempts to distort or co-opt or otherwise pervert what is meant by "permaculture." There was a phase where some militant vegans insisted that permaculture "required" veganism. There was an idea - prior to current issues of cultural appropriation - that permaculture had to include some kind of "indigenous spirituality." And so on...some of these may still be propagating in subculture niches for all I know. At the same time, none of these seems to have prevailed over time, and the relatively un-altered core of the holistic design system remains available for those who truly seek it.
4) To use the rocks and river metaphor, and throw in some river rafting terminology - what I have observed over time is that too many in permaculture subcultures fail to notice the default culture rocks they are already wrapped on, thinking they are floating along dodging rocks while they are actually stuck on some rocks and don't realize it. For example, the rock of (mostly unconsciously) replicating unsystemic interpersonal behaviors and governance within the subculture, which has consistently foiled all attempts over four-plus decades to organize effectively at broader scales for mutual support, benefit, and impact, beyond individual efforts and isolated group niches. Or the related rock of hyper-individualistic culture that pervades most industrial societies, in particular the USA and Australia, leading to a focus on 'homesteading' and individual efforts and the lack of social cohesion and collective effectiveness within the subculture that you mention.
And then there's the rock of "the political spectrum" - that spectrum being defined by default culture, and being dysfunctional and problematic from a whole systems perspective. Why would we want to be anywhere on it? As Kalle Lasn describes in his book "Culture Jam," this is a case of allowing others to control the narrative - the story that is told about, and even by, us and that shapes others' ideas and beliefs about permaculture and the people who engage with it. A question then arises as to how permaculture as a design system might lead practitioners to define their own "political" spectrum that does not subjugate itself to that of default culture. As William Blake says, "I must create my own System, or be enslaved by another Man's. I will not Reason and Compare - my business is to Create."