Anyone who believes that the hard problem to solve with estimation is getting people to give you some estimate before starting a task is definitely very new to this field, or has been extremely lucky in the projects they got to work on...
This is not what I'd describe as automation, a human still has to do the actual estimation. This just enforces some validation that requires a human to fill in the field. It actually does it in a kind of annoying way too because Jira checks the change and rejects it after the user makes an input (though I suspect with a user generated rule that would be difficult to do).
I like how he makes it required, and then immediately sets the estimate to 0, presumably to bypass the new requirement.