I can also vouch for LG not doing anythign scummy. Do you even have open wifi near your TV? I don't, all the dozens of neighborhood routers are all password protected by default from the telecom. You'd have to intentionally make an open network these days, unlike 15 years ago when the situation was the opposite.
I live in an apartment complex with a lot of neighbors and a fair amount of churn, so I have actually seen open networks nearby. I also can't be sure that someone won't move in and create a new one.
What are you odds for living near a 2 bit hacker wannabe? Plus if they were actually malicious, I'm sure there's worse things that are more effective they could do than making your TV update its firmware without your consent.