'what time shall we put here?'
'what's the longest hangover you ever had?'
'let's put 72 hours'
I feel like the only way to be wrong for this class of problem is to believe that there's a singular right answer. Just pick something reasonable (like how weekends are a fairly common thing, so don't make it shorter than 48 hours). Start there, then see how much of an issue persists. No matter what, at scale you'll find someone complaining that the number is too little, and people complaining that it's too much. Eventually you just have to tell the complainers to deal with it.
Cyber attacks will frequently happen on a Friday just for this scenario, they anticipate no ones looking over the weekend.
Blocking a maintainer from pushing updates for a full month after changing their e-mail would be obviously absurd. So Github would have to add a way of enabling maintainers to super-uper-duper confirm the change and cut the delay short. Which is likely not currently possible, hence starting with a shorter delay.
Talked to NPM about this when it went viral, and once again all they could say was enabling package signing, even optionally, would discourage inexperienced people from contributing packages as they would be pressured to learn basic security and key management.
Sorry, if you are unwilling to take 10 minutes to learn how to sign your code, you have no business maintaining software releases millions of people depend on. Full stop.
But NPM will not even make it -optional- and rejects all PRs to implement this going back a decade. So no one feels pressured into basic security. Cool.
Even when you drop off food at a food pantry for consumption by strangers there is a basic expectation it is not spoiled or dangerous.
The crux of the problem is right here.