I do have it isolated from other devices on my network, though.
Not GP, but I do so to make sure my TV doesn't try to connect to a different network. I provide specific IP addresses to the ethernet-connected interface and then block those IP addresses.
I suppose I could also move the TV to an isolated VLAN, but I spent months (the device was purchased nearly, or perhaps even more than, a decade ago) monitoring network traffic to determine to where (via DNS queries and packet captures) my TV was trying to phone home and blocked all egress for the TV and ingress from the sites/IP addresses to which the TV tried to connect.
I suppose that newer TVs might be sneakier (with the kind of WiFi surfing mentioned in TFA and/or installing cellular modems) in their attempts to bypass user control and when I need a new TV, I'll burn that bridge when I come to it.
But for now, my TV can't phone home. Or I'd have thrown it away years ago.
It's actually a lot faster now (it's an 8 year old TV, their OS can get a little heavy on older models)