Non experts have to rule on expert subjects all the time - sometimes this goes hilariously wrong (like the internet being a series of tubes) but usually what happens is that the non-expert relies on the testimony of experts to make their judgement.
Politicians aren't expected to be experts due to the immense breadth of subjects they need to consider - they're expected to consult experts. Whether an individual politician is an expert[1] is pretty irrelevant.
All of these statements are about our general expectations of politicians - whether you think politicians adhere to that point or have comments on specific politicians is beside the scope of my comment. As a less controversial example it might be good to instead consider how judges operate who are expected to provide well reasoned judgements on subjects they know nothing about.
1. Sometimes those former expert politicians are the worst of all since they _think_ they know the way things are and won't listen to actual experts but they've been out of the industry so long that they've lost their familiarity with the subject.
>sometimes this goes hilariously wrong (like the internet being a series of tubes)
That didn't go hilariously wrong, though - the internet is a series of tubes. Not physically (copper cables aren't tubes) but he obviously wasn't talking about specific stuff but broad-strokes analogy (his exact line was "It's not a big truck. It's a series of tubes."), and his description was basically accurate.
