I believe we're merely disagreeing on the intent of the ruling, something that I imagine we will see actually play out in this case.
From the arguments I am seeing made from the ACLU side, the basis is what I have expressed. The town cannot be burdened to find outside religions to achieve a balance, and cannot discriminate against volunteers. The piece you cite merely clarifies this that the government should not be put in a position of making judgements on which religions or how often they get to speak. A first-come first-serve basis works better in this regard.

This is also the interpretation of Galloway that has been used by the FFRF, AHA and ACLU to defeat similar laws to KPB's in other places in the country, so I would say that there is precedent for this interpretation being correct. Again though, we will likely need to see what a court says about these differing interpretations, and it'll probably go to the State SC or 9th Circuit before it's fully resolved.