A: Privacy matters! B: Why should you care if you have nothing to hide? A: If you have nothing to hide, then give me the password to your Facebook. B: I don't trust you with that, but I trust my governments and relevant authorities.
The point is that B's faith in authority is flawed as the "powers that be" are an eternally shifting target. By agreeing to government surveillance, you place trust in every subsequent government, even the ones you would rather not.
Side A abuses (legal, governmental) power, and instead of "lynching" them for that, we turn the issue into "this will become bad only because of side B will do the same". To me it looks like someone supports side A, and wants to limit the "badness" of whatever they did, but still can't support the thing, so they find the way out by claiming that the other side will do something bad with that data, as if the collecting the data (chats,...) isn't bad enough by itself.
I understand your analogy with friends and facebook, and explaining that stuff to your grandma in this way would probably work... maybe even better if you used "your neighbor Sally works for the government, she could read your chats too, do you really want that?"... but on a technical "forum", it (to me) gives off very politically biased vibes.
I think it's more likely to get broad support when framed as us vs. them where "us" is normal working people regardless of political affiliation and "them" is our government elites trying to spy on us.
The current ones are already abusing their power, and the other one might hypothetically do something, if and when and if at all.
This is like Alice making it legal and then punching you in the face and instead of you "punching back", you say "this is fine, but Bob is bad, because if he gets voted in, he'll punch harder".
