I don’t have one of these, so I could be way off, but the idea of a one-handed chainsaw just seems inherently unsafe to me. Aside from any issues with just controlling the thing, the temptation is going to be put put your “free” hand out in front to reach for things you’re cutting to hold them still, and the size of this device means you could naturally just let it rest it down at your side like a power drill or staple gun something… but it’s a chainsaw. An actual chainsaw with two hands means you hold it in front of you, and you don’t just let it hang down at your side. Maybe I’m wrong and this thing isn’t any more dangerous than a butter knife.
On the other hand, if you buy two you could double wield like a character out of a post-apocalyptic video game…
But you have those sturdy gloves that come with it! Your hands will be impervious to all harm with those bad boys on 
. On a serious note, I think you bring up a valid point, but these don’t quite have the power and size to have the same kickback or do the damage a full-size chainsaw would do. I am not saying ignore any of the same safety precautions and act dumb (as you said it is still a chainsaw), but the difference between a full-size chainsaw and one of these is pretty big.
Maybe it’s fine. Again, I haven’t actually even got my hands on one… but those hands still have all their fingers, so I’m going to err on the side of caution.
Another issue: While I haven’t heard anything specific about this kind of device, I have heard/read more than a few people talking about how unsafe the chainsaw wheel for angle grinder is. The issue there seems mostly to be about how difficult it is to control or, rather, how easy it is to lose control suddenly. The chainsaw structure being good for cutting, but also tends to jump and skitter across a surface before biting into whatever it’s cutting, and that’s using both hands. Seems like this thing would have similar issues, and that one handed grip means the user is relying on an awful lot of grip/wrist strength.
Maybe this thing isn’t any scarier in real life than a pair of scissors, but it just looks like a trip to the ER to me.
Edit: I notice in the pictures they aren’t even wearing the gloves. lol!