5G connectivity is cheap. You can put a 5G modem in pretty much any device for $10 or less, and pay roughly $2/year in subscription fees. My local water utility with ~900 subscribers pays $2/year for 5G connectivity for water meters, and I have no doubt you can get it much cheaper at scale.
They don't even have to tell you about the 5G modem. It could exclusively be used for exfiltrating data about your viewing habits. It's virtually undetectable and more or less impossible to block. The TV could behave nice on the Wifi, you can block all the DNS servers you like, it would still be able to phone home.
You are asking for $20 increase in BOM, which means they somehow has to extract $20 from your private data, which is hard.
And if they're not expecting to make $20 over 10 years selling your data, it hardly seems worth risking your reputation over.
Comcast sets up a secondary wifi network on their routers in your home that they use as the backhaul for smartphones. Why wouldn't they make a deal with LG or whoever to use that data? We've already established they'll do about a half-a-Stuxnet to get at this data, you're telling me they won't do a couple bulk deals with common ISPs?