To my knowledge, as said, this has happened twice... maayyybee three (I've a nasty feeling there may have been a third time? But if so this is going back many many many years) in all my time of playing/DMing (15+years of playing, probably nearing a decade of DMing) so that's not a whole lot. I don't think it's endemic. But I will agree that the amount in the last election is worrying.
IMO there are three levels of rules enforcement
The first is just asking people to Not Do The Thing. You'd be suprised how often this works! Most of the time saying 'hay, don't do this!' is dicinsentive enough.
The second is more heavily policing The Thing. I feel this may kinda be where we're leaning to now? I expect for a time at least we will be heavily watching a few elections for this sort of thing, and making sure everyone is playing by the rules, and more firmly enforcing when they don't. With a little luck, this will be more than enough to keep things fair.
The third thing to do - if that doesn't work, or if that's proved unwieldable due to the amount/style of rulebreak, is considering mechanical options - such as some of the things listed above.
The problem with mechanical options is that they can be an impedement to roleplay, and have other delaterious effects. A great, and somewhat similar, example is the property changes. We were concerned that properties were just being passed from friend to friend over years, meaning a lot of players didn't get a shot. So we introduced the auction process. In many ways this was a good change, but it also has downsides- it hinders the roleplay of certain factions and so on. It was a neat solution to the problem, but not one without its own issues. The same is true of most mechanical soltuions.
It may be that in the coming weeks/months/years, we... instead of getting less... get more and more election rigging issues. If that's so, then we may have to look at more mechanical solutions. But for now it seems small enough I think we can continue to work from a purely DM enforced standpoint.
This too shall pass.
(I now have a DM Discord (I hope) It's DM GrumpyCat#7185 but please keep in mind I'm very busy IRL so I can't promise how quick I'll get back to you.)