The Purezone is a standard Class B digital device like almost every other electronic equipment that is found in the home.  The specific text on the card that the customer showed is legally required text for all electronic devices that operate above 8 kHz so requires FCC certification and is to be used in the home (which requires Class B certification as opposed to Class A for commercial/business uses).  

Click here for reference: https://www.law.cornell.edu/cfr/text/47/15.105

Or https://pubmed.ncbi.nlm.nih.gov/25162422/ which also stated that:

The results of this study mitigate concerns about using Wi-Fi devices close to PM: none of the PM tested exhibit any degradation of their performance, even when exposed to RF field levels five times higher than those allowed by current international regulation (20 W EIRP). In conclusion, Wi-Fi devices do not pose risks of EMI to implantable PM. The immunity level of modern PM is much higher than the transmitting power of RF devices operating at 2.4 GHz.

The electronically unintentionally noisiest part of the system is the cassette motor but that is underwater in the skimmer so will not be an issue for anyone standing over the unit.  The intentional radiation is only at around 2.4 GHz in frequency for Bluetooth Low Energy (BLE) and for Wi-Fi.  So if you have Wi-Fi in your home then this will be no worse/different than other Wi-Fi devices you have.