the graph kind of looks like a U if you squint at it
I think this visual effect could plausibly be explained by polarization, without there being any real correlation between extremeness and concern about AI x-risk. Most politicians aren’t moderate, and most politicians aren’t concerned about AI x-risk. So the distribution of ideology scores of politicans at the bottom (not concerned about AI x-risk) is bimodal, and the distribution of ideology scores of politicans near the top (very concerned about AI x-risk) is bimodal, but the whole distribution is thicker at the bottom than near the top. The density of non-x-risk-concerned moderates could be high enough to be close to saturating our ability to perceive density of dots in this graphic, so that the actually much denser regions leftward and rightward aren’t readily apparent to be much denser. But higher up, the dots aren’t dense enough to saturate our ability to perceive their density, so it is visually obvious that there are more at the extremes than in the middle.
This is not legal. They could donate to a super PAC that supports candidates that support AI regulation, though (e.g. Public First, or they could start their own super PAC).