while I don't agree that they're better at trading, your response is clearly wrong here.

A congress person is able to constantly make decisions with imperfect information and be successful doing it, one can imagine that skill could give them an edge when trading.

But the reason I don't agree with it is because they're using 3rd part managers. It's far more likely that they're advising.

However, the way to put this to bed is to compare their accounts with those of others being managed by the same team. do they out-perform, under-perform, or roughly match those other accounts? There's your answer.