It would be the irony of ironies if the Green Party was Sinema's Achilles Heel in November.
Green Party candidates in AZ tend to over-poll and under-perform once E-Day actually hits....
Sure if it's a nail biter that might well make the difference, but my question would be why didn't they also poll the Libertarian Candidate, since I believe both are waging write-in campaigns only, and their names won't appear on the November ballot (Am I mistaken?).
To me it looks more like symbolic statement of opinion regarding Sinema's shift in political positioning that has frustrated some on the "Political Left", combined with essentially more a "non-of the above" option.
As we well know, most of these voters will not write-in a 3rd Party Candidate for US-SEN in November, but will likely put the clothespin on their noses and pick a choice, or sit out the election altogether.
I know your post was regarding the potential irony, so not taking a swing at all on that, and yes collectively 3rd Party Candidates can do pretty decently at times in AZ compared to many other States if enough voters are dissatisfied with their choices, but not convinced this will be the case here.