[celtain]

A member of congress voting for $10B of useless defense spending because they're heavily invested in the relevant aerospace company isn't committing insider trading.

Perhaps this is unnecessarily pedantic, but what you're describing is a "conflict of interest" problem, not an "insider trading" problem. You can have either problem without the other, and depending on how you crack down on insider trading, it could be completely ineffective at solving the conflict of interest problem.