That's the point: this is not research, but whatever is going on at Google, the explanation has to account for examples like these. It's simply one observation that you cannot discount.
I just tried searching again a few times with new private windows, and "email" alternates between first and fourth suggestion for trump. But the more important point is the absence of the suggestion for clinton: we know it's been in the news extensively, we know people searched for this phrase a lot, and now "email" has been removed from the suggestions only for Clinton. I tried searching a few more U.S. politicians, and for all of them "e" autosuggests "email" somewhere between first and fourth place. So the complete absence for Clinton does not look like a generic algorithm change.
The question doesn't need answering any more than any other arbitrarily selected individual query needs an answer. Why does "trump helsinki" have zero suggestions? Why does "bill oreilly sex" have zero suggestions? Why does "alex jones sandyhook" have zero suggestions? I used right-wing examples because I presume any celebrity or left-wing examples will be considered evidence in favor of your position, but there are plenty of examples all over the place.
Yes we have. Further observation shows Google removes autocomplete for controversial items, like "Russian Investigation" for Donald Trump. If that example doesn't answer your question then you have confirmation bias.
When I type "Donald Trump R" I don't see any autocomplete for "Donald Trump Russia" despite plenty of news coverage on this topic. So what? This isn't proof of anything. I can indeed discount "one observation" because it is literally a single search query used to draw a conclusion about an insanely complex system that processes billions of queries a day. I am open to the possibility that google is manipulating search results, but to demonstrate this you need to account for many other possible search queries that produce seemingly unexpected results. Dissecting one politically charged query and claiming it is proof of google's malfeasance doesn't make sense. Anyone can string together a couple strange query results to support their own subjective narrative about what should appear and the supposed sinister machinations behind the query results.
I just tried searching again a few times with new private windows, and "email" alternates between first and fourth suggestion for trump. But the more important point is the absence of the suggestion for clinton: we know it's been in the news extensively, we know people searched for this phrase a lot, and now "email" has been removed from the suggestions only for Clinton. I tried searching a few more U.S. politicians, and for all of them "e" autosuggests "email" somewhere between first and fourth place. So the complete absence for Clinton does not look like a generic algorithm change.