I'm pretty sure the rule is that for every 6 feet of snake(or is it 8 feet? One of those) you should have another person with you--just in case. So I think they just mean the normal 'be aware' warning to not handle a large animal alone in case you get over powered. Although it's unlikely, you never want to be that one statistic!
I had heard the same warnings on adult RTBs on the care sheets I read(following the rule of big snakes, when it gets big enough..have someone else around to help if something goes wrong)
I'm not a dumeril's owner, but a boa owner. When Nagini is a big big girl, I won't be chilling out with her without someone else around if it could go wrong. A snake can bite and a snake can strangle! Doesn't mean they will but.. You know, never hurts to be cautious I guess.
But that's my take on it!