While I know this is possible and have done it sometimes for fun, I would never spend any appreciable amount of time doing it at a job.
If you are at the point where you need to modify commit timestamps to satisfy some micromanager, it's highly likely that there are other things wrong with them that will lead to you searching for a new job fairly soon.
All I was saying is that these two are very likely mutually exclusive.
Sure, it's hypothetically possible that I have a micromanage-y boss who only tracks my commit times and nothing else. But really? That's the same boss who's going to mentally think you're "not a team player" because you left an hour early for your son's birthday party. That's the same boss who's going to obsessively tracks how many vacation days you "accrued" and insist on you coming in when you're sick if you don't have any left. Let's not kid ourselves.
If you are at the point where you need to modify commit timestamps to satisfy some micromanager, it's highly likely that there are other things wrong with them that will lead to you searching for a new job fairly soon.