Reasons to treat these situations differently:

1. The executive is doing very obvious insider trading, you can point at exact trades and bets that are clearly being made based on inside info. That's very different than the statistical arguments made about congressional portfolios.

2. Congress isn't privy to the same kind of inside info. Congress will know about changes in government spending with a few weeks to a month or so of lead time. The executive insiders were timing trades down, literally, to the minutes before the start of military action.

Basically that's a terrible whataboutist game you're playing.