Do not ascribe to malice that which can be explained by ineptitude. Or something like that.
My understanding is that the result on Google, both displayed search results and auto-completion suggestions, are based on a large number of factors including (wait for it) your personal past history of typing, and the most popular results.
Assuming that a "voting for ..." search would autocomplete with both main candidates equally assumes that there are as many people typing one candidate as the other. That is an unfounded assumption that is likely false. I searched a few times for a third-party candidate and lo! my autocomplete changed. The horror! Bias! Lynch them! Or, wait, maybe if I were searching for widgets that might be a good idea. Maybe if I were looking for somewhere to vacation, that might be a good idea. Maybe under circumstances that are not so emotionally incendiary, we might want exactly this behavior because it works very well.
Any evaluation that demonstrates bias and is shocked by the results (or merely reports them) must prove unequivocally that the assumption of a lack of fundamental underlying bias in the data exists. A fundamental equality of data (e.g. the same number of web sites for the two candidates, the same number of twitter posts, etc.) is unlikely to be true in any of the cases being discussed in this thread.
In other words, the original posting is not news. It is, to use the current vogue terminology, fake news. Lying with statistics. Click bait. Something to be ignored.