Wired in series would present a 16 Ohm load. Not really a big deal, but you'd need to increase the volume level to get the same output.
The real problem with wiring speakers in series, is they are not a fixed 8 Ohm load, but a reactive load that changes impedance depending on the frequency of the signal driving them. The driver's native impedance is balanced with the crossover network to allow a linear frequency response. When the loads in are series with each other, the impedance peaks grow even larger, while the low points don't pile up as much. Since the peaks usually exist in the treble range, this would have the effect of rolling off the highs, and thus causing a less than linear response.
You really want each speaker to be connected to its own amplifier output, no parallel wiring, and definitely no series. Impedance-matching switches only go so far. They're still not some thing you want involved in a high quality playback system. But for in-store music, who cares? And he's not thinking about using Axiom speaker in the shop either; quality is not high on the list.
