I have no idea how they select which SNPs to test on the Y chromosome, and was actually surprised that they bothered. I suspect is has more to do with matching and/or ethnicity prediction than haplogroups.
My recommendation is to just to the real Y-DNA test. The 12 marker is only $49, and it gives enough data to predict your basic haplogroup and possibly even further down the tree. For example, in my project 12 markers is enough to predict R1b1a2 for some, but others have 37 and only show I1. From there, you can then go back and see if ancestryDNA happens to have tested any SNPs of interest. You can also use your results to join a surname project (presumably Wiley). The project admins will typically put you in a subgroup, and that will help determine how much (if any) more you need to test. That all depends on your goals.