The only problem with that idea is your modem. I think the ISP usually has a certain level of access to it; especially if it is an ISP-provided one.
As with anything, there are levels of concern for different things. Sometimes, it’s more hassle than it is worth to act on our privacy concerns. Sometimes, there’s just really nothing we can do about it, and we have to just accept things the way they are. Other times, we figure out a ways of mitigating such risks.
In the case of the ST hub, I hadn’t actually committed to that particular one yet, but I’m thinking about it now. I guess, since everything goes through the cloud anyway (V1), I could have it on a ‘Guest’ network and never see any difference other than knowing that I’m safer (marginally, but it is what it is; one more area where I could improve my firewall). I will be looking into it now. 
Thanks for the reminder.