No I'm afraid, the guest network on Google Wifi runs on both the 2.4 and 5 GHz bands and there's no settings to alter that.
Typically, the most common workaround for this is to add a 2.4 GHz only access point to your setup, perhaps repurposing an old router just for this purpose. Alternatively, if this is critical to you or you have lots of these types of devices, you would need to consider a different Wi-Fi solution than Google Wifi as unfortunately Google haven't made any announcements or feature changes to make working with these poorly designed 2.4 GHz only devices easier.
