If she wanted to insult him about having dementia, why didn’t she mention the dementia?

If she wanted to help his campaign, why didn't she mention the campaign? We're both inferring what she was referring to, so the double-edged nature of this question should be patently obvious. I'm a little shocked it was even asked.

It makes more sense for it being about the campaign because, again, she is begging Ivanka to help Trump.

This is included as an example in an article that starts with "Donald Trump on Saturday was hit with an avalanche of criticism." The author of the article pretty clearly agrees with me. Additionally, you are ignoring the "politics aside" part of the comment which strongly implies there is a differing of politics here that Jil wants to transcend. You are required to infer both the context and the content of the post itself for your position to be true, so it certainly does not make more sense.

Because helping him helps him win.

It's facetious. She doesn't expect it to happen.