It can be obvious and go to the heart. I'm not sure Wilfred Owen's Dulce et decorum est is anything other than straight down the line, but it made me cry when I first read it.
That said, maybe the subversion is in how the reality is contrasted with the marketing.
I see 'subversion' as more broad. In good poetry, subversion is constantly happening at a micro level, through playing with meaning, meter, word choice. I think it's very easy to identify AI-generated poetry because it lacks any of that -- but on the flip side, if you don't understand the rules, you don't understand how to subvert them.
Even in Dulce et decorum est -- though the meaning's straightforward, there are plenty of small, subversive (and pretty) ideas in the meter. For example, the line "He plunges at me, guttering, choking, drowning" is an unexpected, disruptive staccato that really sounds like guttering, choking, drowning. It's a beautiful poem and is overflowing with such examples.
(I think this applies to art as a whole, not just poetry.)
Even the last line of the poem is a twist on expectations and plays on the irony of nationalism and patriotism, the beautiful latin phrase that inspires young men and the harsh reality of trench warfare that it leads them into. No LLM is going to do that.
Funnily enough, the phrase doesn't even shy away from the fact that you are dying for your country. The poem really gets at the fact that the way you die is horrible and that in itself is enough to counter the romantic notion. The reality of dying for your fatherland is not cleanly and painlessly dropping from your mount in a heroic and successful cavalry charge, even if that is good.
That said, maybe the subversion is in how the reality is contrasted with the marketing.