You can't police that. The only thing you can reliably do is allocate power. If you allocate power to prosecutors to prosecute elected officials, you've basically handed them the power to decide who people are allowed to vote for. This power gets abused in virtually every country where it's normalized.
The safeguards within the justice system are appropriate for prosecuting individuals. They are not set up to handle matters of national importance that could way the direction of the country or deprive tens of millions of voters of their preferred candidate.
If you don't believe that, then consider a hypothetical system where we allow prosecutions according to the standard you propose. Except only Texas courts and prosecutors have jurisdiction.
The safeguards within the justice system are appropriate for prosecuting individuals. They are not set up to handle matters of national importance that could way the direction of the country or deprive tens of millions of voters of their preferred candidate.
If you don't believe that, then consider a hypothetical system where we allow prosecutions according to the standard you propose. Except only Texas courts and prosecutors have jurisdiction.