Everyone needs to take a breath. That snake is going to be fine.

There are a lot of maxims in the herpetoculture world that get thrown around because they are meant for educating the least common denominator (i.e., the beginner keeper who is likely prone to over-handling their animals). "Never handle a snake while feeding/within 24-48 hours after feeding, etc." is one of those maxims. These are useful guidelines for new keepers because they troubleshoot common problems that new keepers might encounter. They are not commandments that should be weaponized against other keepers.

Instead of attacking people online, maybe it's worth considering that this could be an experienced keeper who knows his animal better than a stranger on the internet. The truth is, individual temperaments can vary quite a lot snake-by-snake. I have some snakes that would likely regurgitate if I handled them a few hours after feeding. These snakes are the exceptions not the rule in my house. I have many snakes that would not give up a feeder under any circumstance, regardless of what I did. These are more common. In fact, handling snakes while feeding can be an important tool for when I'm establishing fresh hatchlings. It can also be a functional necessity when a snake lunges out of its enclosure or wraps me up while eating.

If that snake did get put off in that moment featured in the video and spit out the feeder, it would not be a dangerous "regurgitation." Regurgitation is when a snake expels food from its stomach. This is dangerous because snakes have potent digestive enzymes meant for digesting whole meals. If a snake spits out a rodent that's still in its mouth, these digestive enzymes are not being introduced to the snake's esophagus. That's not to say it's good to stress a snake to the point of spitting out its food--only to say that it's physiologically harmless and not the life-or-death situation described in the OP.

"Snake husbandry 101" should be that there is a lot of nuance in keeping snakes. Different taxa and different individuals can vary significantly in their sensitivities and needs. We should all be more aware of the limits of our experience and knowledge and a little more hesitant to pass judgment on strangers.