I think it's a stretch to assume this is part of a coordinated campaign to manufacture consent for ACT. KKH has been critical of bad research in ME previously, so unless he's done a full 180, I can't see it.
It's vaguely possible that a Guardian editor got the idea to write about acceptance from a PR person with an agenda (or the SMC), and then reached out to KKH, but that doesn't quite fit the pattern.
E.g., the SMC would offer their own experts, and would push for that over suggesting an editor commission a wildcard like a person with ME. We know that's their modus operandi, because it puts them in control.
And most PRs who pitch story ideas do so because they have something to sell. The story is just the avenue for getting free coverage. So they would have a client who's just written a new book, say, which also happens to address the issue or solve the problem for the reasonable price of £9.99...
It seems more likely that KKH pitched the article, the editor responded with a counterproposal that fit into their current plans, and then they mutually agreed upon the final subject to be written.
Then there's the editing process itself, which probably stripped out anything that seemed like a tangent or a distraction, and therefore resulted in even less nuance, in order to stick to a wordcount and rigid topic.