There is enough mud to be thrown either way. As a country allied with the US (in general) I'm much less concerned by America's government, but the distrust of anything non-western... I mean, we are all people wanting to make a living in this world with much more in common than most are aware of.
Italy is (and was) most certainly an 'allied' country to the US and it didn't stop them either.
But that is precisely why people distrust the companies.
b) didn't they change their unpublishing policy after that event?
My Firefox currently looks like this: https://dump.thecybershadow.net/0177f0cecdf6ad3b65158858a210...
The new Opera, i.e. every Opera after Version 15, is a Chromium fork.
That means it carries with it all the small and large behaviors like: Auto-updating. It also has literally no upside over using Opera v12, which still works fine for most things nowadays; and mostly no upsides over using just Chrome, or any other flavor of Chromium.
As such, getting rid of it after this acquisition gives only upside for the safety-conscious user.
Unfortunately, I still use Google Services on my phone to use Google Play store for apps. I see no viable alternative for now.
I trust the security acumen of the 'many eyes' who work on that project much more than Opera or Firefox. And Google doesn't vacuum up any data unless you volunteer it in Chrome. That's been proven.