Flywheel does not MITM SSL connections; it does not proxy SSL at all. If you just mean "MITM" in a generic sense, the fact that you believe you have "data sovereignty" is interesting since we're talking about unencrypted HTTP here. Nearly all ISPs and mobile carriers undertake proxying and extensive analysis and manipulation of in-the-clear HTTP traffic. We agree that users need to opt into this feature -- since you have to trust Google to proxy your traffic, after all -- but it's important to keep in mind that many other parties on the path between you and a website already do transparently proxy your unencrypted traffic.
Regarding the Third Party Doctrine, the fewer third parties with access to the information, the more sovereign over the data the remaining parties are. But I agree with you that ISPs and mobile carriers are other companies who intercept, profile, sell and partner away plaintext information - and indeed in the case of at least some mobile carriers encrypted communications too.
I agree with the assessment that this is an opt in feature. I have spoken about the reasons I won't be opting in. (In my opinion it is a very bad trade.)
Definitely agreed that many other parties have access to the data. I disagree that this is an argument to add another.
[By the way, thank you very much for taking the time to speak on HN about Flywheel from your position. :)]
I absolutely agree with your rationale for not wanting to opt in; we appreciate that this is a highly privacy-sensitive topic and one that users need to make up their own minds about.
Flywheel does not MITM SSL connections; it does not proxy SSL at all. If you just mean "MITM" in a generic sense, the fact that you believe you have "data sovereignty" is interesting since we're talking about unencrypted HTTP here. Nearly all ISPs and mobile carriers undertake proxying and extensive analysis and manipulation of in-the-clear HTTP traffic. We agree that users need to opt into this feature -- since you have to trust Google to proxy your traffic, after all -- but it's important to keep in mind that many other parties on the path between you and a website already do transparently proxy your unencrypted traffic.