I think this is spot on. If someone says something hateful, and I retweet it, am I not also saying something hateful? Say I don't retweet the actual comment, but instead respond w/ "Have some money." Is that not still an endorsement of the hateful speech?
Ultimately, I think we can view hatred as a kind of ignorance and fearfulness of the unknown, and therefore as a kind of stupidity.
It logically follows that endorsing a stupid candidate is itself a form of stupidity.