If it had Ethernet ports I'd be tempted to just use my own wifi router and put the ISP's Trojan horse in a Faraday cage. All ISP-controlled hardware should be treated as just another untrusted WAN hop.

When I signed up with them, they were actually trying to withold access to the config web UI from customers and then charge extra just to enable Wifi. My response was exactly that - "fuck that" and put my own router in front of theirs.

(That was years before the other incident - since then they had dropped that idea and "generously" given customers access to the config UI)

These devices usually have detachable antennas, so just unscrew them