I get why people want this, and honestly, insider trading rules make sense. But banning all stock trading feels like too much. Regular folks can invest, so why treat public officials like they can't be trusted at all? I just don't see the need for such a wide rule.
Just like you said "Regular" folks, this only means one thing. They are just ordinary people who doesn't have an access to the government fund unlike these politician who could easily manipulate taxes from honest paying civilians.
The practical problem is that banning stock trades would scare away talented people from public service, since they'd lose a normal way to save for retirement. You do make a fair point about not knowing where funds come from, and I'm not sure how to answer that.
You're right that officials have more control over money, and that's a real worry. Still, I think the answer is better oversight, not a total ban. Most of them probably just want to invest like everyone else, so I can't get behind the sweeping rule.